A scientific calculator is designed to calculate problems in science, engineering, and mathematics. They have almost completely replaced slide rules in almost all traditional applications, and are widely used in both education and professional settings. This program was written using the C# programming language. 

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace SC
{
    public partial class frmScientificCalculator : Form
    {
        int sign = 0;
        double num1;
        double num2;
        int add = 0;
        int sub = 0;
        int mul = 0;
        int div = 0;
        int modBit = 0;
        Boolean fl = false;
        String s, x;

        public frmScientificCalculator()
        {
            InitializeComponent();
        }

        private void btn1_Click(object sender, EventArgs e)
        {
            if (sign == 0)
            {
                txtInput.Text = txtInput.Text + Convert.ToString(1);
            }
            else if (sign == 1)
            {
                txtInput.Text = Convert.ToString(1);
                sign = 0;
            }
            fl = true;
        }

        private void btn2_Click(object sender, EventArgs e)
        {
            if (sign == 0)
            {
                txtInput.Text = txtInput.Text + Convert.ToString(2);
            }
            else if (sign == 1)
            {
                txtInput.Text = Convert.ToString(2);
                sign = 0;
            }
           fl=true;
        }

        private void btn3_Click(object sender, EventArgs e)
        {
            if (sign == 0)
            {
                txtInput.Text = txtInput.Text + Convert.ToString(3);
            }
            else if (sign == 1)
            {
                txtInput.Text = Convert.ToString(3);
                sign = 0;
            }
           fl=true;
        }

        private void btn4_Click(object sender, EventArgs e)
        {
            if (sign == 0)
            {
                txtInput.Text = txtInput.Text + Convert.ToString(4);
            }
            else if (sign == 1)
            {
                txtInput.Text = Convert.ToString(4);
                sign = 0;
            }
           fl=true;
        }

        private void btn5_Click(object sender, EventArgs e)
        {
            if (sign == 0)
            {
                txtInput.Text = txtInput.Text + Convert.ToString(5);
            }
            else if (sign == 1)
            {
                txtInput.Text = Convert.ToString(5);
                sign = 0;
            }
           fl=true;
        }

        private void btn6_Click(object sender, EventArgs e)
        {
            if (sign == 0)
            {
                txtInput.Text = txtInput.Text + Convert.ToString(6);
            }
            else if (sign == 1)
            {
                txtInput.Text = Convert.ToString(6);
                sign = 0;
            }
           fl=true;
        }

        private void btn7_Click(object sender, EventArgs e)
        {
            if (sign == 0)
            {
                txtInput.Text = txtInput.Text + Convert.ToString(7);
            }
            else if (sign == 1)
            {
                txtInput.Text = Convert.ToString(7);
                sign = 0;
            }
           fl=true;
        }

        private void btn8_Click(object sender, EventArgs e)
        {
            if (sign == 0)
            {
                txtInput.Text = txtInput.Text + Convert.ToString(8);
            }
            else if (sign == 1)
            {
                txtInput.Text = Convert.ToString(8);
                sign = 0;
            }
           fl=true;
        }

        private void btnnine_Click(object sender, EventArgs e)
        {
            if (sign == 0)
            {
                txtInput.Text = txtInput.Text + Convert.ToString(9);
            }
            else if (sign == 1)
            {
                txtInput.Text = Convert.ToString(9);
                sign = 0;
            }
           fl=true;
        }

        private void btnZero_Click(object sender, EventArgs e)
        {
            if (sign == 0)
            {
                txtInput.Text = txtInput.Text + Convert.ToString(0);
            }
            else if (sign == 1)
            {
                txtInput.Text = Convert.ToString(0);
                sign = 0;
            }
           fl=true;
        }
        private void reset_SignBits()
        {
        add = 0;
        sub = 0;
        mul = 0;
        div = 0;
        modBit = 0;
        fl = false;
        }
        private void btnAdd_Click(object sender, EventArgs e)
        {
            if (txtInput.Text.Length != 0)
            {
                calculate();
                reset_SignBits();
                add = 1;
                sign = 1;
            }
        }

       
        private void btnMinus_Click(object sender, EventArgs e)
        {
            if (txtInput.Text.Length != 0)
            {
                num2 = Convert.ToDouble(txtInput.Text);
                calculate();
                reset_SignBits();
                sub = 1;
                sign = 1;
            }
        }

        private void btnTimes_Click(object sender, EventArgs e)
        {
            if (txtInput.Text.Length != 0)
            {
                calculate();
                reset_SignBits();
                mul = 1;
                sign = 1;
            }
        }

        private void btnDivide_Click(object sender, EventArgs e)
        {
            if (txtInput.Text.Length != 0)
            {
                calculate();
                reset_SignBits();
                div = 1;
                sign = 1;
            }
        }

        private void btnEqual_Click(object sender, EventArgs e)
        {
            if (txtInput.Text.Length != 0)
            {
                calculate();
                reset_SignBits();
            }
            sign = 1;
        }

        private void btnDot_Click(object sender, EventArgs e)
        {
            int i = 0;
            char chr = '\0';
            int decimal_Indicator = 0;
            int l = txtInput.Text.Length-1;
            if (sign != 1)
            {
                for (i = 0; i <= l; i++)
                {
                    chr = txtInput.Text[i];
                    if (chr == '.')
                    {
                        decimal_Indicator = 1;
                    }
                }

                if (decimal_Indicator != 1)
                {
                    txtInput.Text = txtInput.Text + Convert.ToString(".");
                }
            }
        }

        private void btnsqrt_Click(object sender, EventArgs e)
        {
            double s,l;
            l = Convert.ToDouble(txtInput.Text);
            s = Math.Sqrt(l);
            txtInput.Text = Convert.ToString(s);
        }

        private void btn1divx_Click(object sender, EventArgs e)
        {
            txtInput.Text = (1 / Convert.ToDouble(txtInput.Text)).ToString();
        }

        private void btnxfoctorial_Click(object sender, EventArgs e)
        {
            try
            {
                long fact = 1;
                for (int i = 1; i <= Convert.ToInt32(txtInput.Text); i++)
                {
                    fact = fact * i;
                }
                txtInput.Text = Convert.ToString(fact);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void btnLog_Click(object sender, EventArgs e)
        {
            try
            {
             if (txtInput.Text.Length != 0)
             {
            double l;
            l = Math.Log(Convert.ToDouble(txtInput.Text));
            txtInput.Text = Convert.ToString(l);
             }
             sign = 1;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void btnLog10_Click(object sender, EventArgs e)
        {
              try
            {
             if (txtInput.Text.Length != 0)
             {
            double l;
            l = Math.Log10(Convert.ToDouble(txtInput.Text));
            txtInput.Text = Convert.ToString(l);
 }
             sign = 1;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void btnex_Click(object sender, EventArgs e)
        {
              try
            {
             if (txtInput.Text.Length != 0)
             {
            double l;
            l = Math.Exp(Convert.ToDouble(txtInput.Text));
            txtInput.Text = Convert.ToString(l);
            }
             sign = 1;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void Form6_Load(object sender, EventArgs e)
        {
    
        }

        private void btnSin_Click(object sender, EventArgs e)
        {
            try
            {
             if (txtInput.Text.Length != 0)
             {
            double l;
            l = Math.Sin(Convert.ToDouble(txtInput.Text));
            txtInput.Text = Convert.ToString(l);
            }
             sign = 1;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void btnCos_Click(object sender, EventArgs e)
        {
              try
            {
             if (txtInput.Text.Length != 0)
             {
            double l;
            l = Math.Cos(Convert.ToDouble(txtInput.Text));
            txtInput.Text = Convert.ToString(l);
             }
             sign = 1;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void btnTan_Click(object sender, EventArgs e)
        {
              try
            {
             if (txtInput.Text.Length != 0)
             {
            double l;
            l = Math.Tan(Convert.ToDouble(txtInput.Text));
            txtInput.Text = Convert.ToString(l);
             }
             }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void btnRound_Click(object sender, EventArgs e)
        {
              try
            {
             if (txtInput.Text.Length != 0)
             {
            double l;
            l = Math.Round(Convert.ToDouble(txtInput.Text));
            txtInput.Text = Convert.ToString(l);
             }
             sign = 1;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void btnFloor_Click(object sender, EventArgs e)
        {
               try
            {
             if (txtInput.Text.Length != 0)
             {
            double l;
            l = Math.Floor(Convert.ToDouble(txtInput.Text));
            txtInput.Text = Convert.ToString(l);
            }
             sign = 1;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void btnTruncate_Click(object sender, EventArgs e)
        {
            try
            {
             if (txtInput.Text.Length != 0)
             {
            double l;
            l = Math.Truncate(Convert.ToDouble(txtInput.Text));
            txtInput.Text = Convert.ToString(l);
             }
             sign = 1;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void btnCeil_Click(object sender, EventArgs e)
        {
               try
            {
             if (txtInput.Text.Length != 0)
             {
            double l;
            l = Math.Ceiling(Convert.ToDouble(txtInput.Text));
            txtInput.Text = Convert.ToString(l);
            }
             sign = 1;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void btnInvSin_Click(object sender, EventArgs e)
        {
               try
            {
             if (txtInput.Text.Length != 0)
             {
            double l;
            l = Math.Asin(Convert.ToDouble(txtInput.Text));
            txtInput.Text = Convert.ToString(l);
            }
             sign = 1;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void btnSinh_Click(object sender, EventArgs e)
        {
               try
            {
             if (txtInput.Text.Length != 0)
             {
            double l;
            l = Math.Sinh(Convert.ToDouble(txtInput.Text));
            txtInput.Text = Convert.ToString(l);
             }
             sign = 1;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void btnCosh_Click(object sender, EventArgs e)
        {
               try
            {
             if (txtInput.Text.Length != 0)
             {
            double l;
            l = Math.Cosh(Convert.ToDouble(txtInput.Text));
            txtInput.Text = Convert.ToString(l);
            }
             sign = 1;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void button24_Click(object sender, EventArgs e)
        {
               try
            {
             if (txtInput.Text.Length != 0)
             {
            double l;
            l = Math.Tanh(Convert.ToDouble(txtInput.Text));
            txtInput.Text = Convert.ToString(l);
            }
             sign = 1;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void btnInvCos_Click(object sender, EventArgs e)
        {
               try
            {
             if (txtInput.Text.Length != 0)
             {
            double l;
            l = Math.Acos(Convert.ToDouble(txtInput.Text));
            txtInput.Text = Convert.ToString(l);
             }
             sign = 1;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void btnInvTan_Click(object sender, EventArgs e)
        {
            try
            {
                if (txtInput.Text.Length != 0)
                {
            double l;
            l = Math.Atan(Convert.ToDouble(txtInput.Text));
            txtInput.Text = Convert.ToString(l);
 }
             sign = 1;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void calculate()
        {
            if (txtInput.Text != ".")
            {
                num2 = Convert.ToDouble(txtInput.Text);
                if (fl == false)
                {
                    num1 = num2;
                }
                else if (add == 1)
                {
                    num1 = num1 + num2;
                }
                else if (sub == 1)
                {
                    num1 = num1 - num2;
                }
                else if (mul == 1)
                {
                    num1 = num1 * num2;
                }
                else if (div == 1)
                {
                    num1 = num1 / num2;
                }
                else if (modBit == 1)
                {

                    num2 = Convert.ToInt32(txtInput.Text);
                    num1 = Convert.ToInt32(num1 % num2);
                }
               
                else
                {
                    num1 = num2;
                }
                txtInput.Text = Convert.ToString(num1);

            }
          }

        private void btnmod_Click(object sender, EventArgs e)
        {
            if (txtInput.Text.Length != 0)
            {
                calculate();
                reset_SignBits();
                modBit = 1;
                sign = 1;
            }
        }

        private void btnPI_Click(object sender, EventArgs e)
        {
            txtInput.Text = Math.PI.ToString();
            sign = 1;
        }

        private void btnCLR_Click(object sender, EventArgs e)
        {
            txtInput.Clear();
            sign = 0;
            num1 = 0;
            num2 = 0;
            reset_SignBits();
        }

        private void btnbackspace_Click(object sender, EventArgs e)
        {
            s = txtInput.Text;
            int l = s.Length;
            for (int i = 0; i < l - 1; i++)
            {
                x += s[i];
            }
            txtInput.Text = x;
            x = "";
        }
       
    }
}