Code:using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; namespace calculator2 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void txtDisplay_TextChanged(object sender, EventArgs e) { } double total1 = 0; double total2 = 0; double answer; private void btnOne_Click(object sender, EventArgs e) { txtDisplay.Text = txtDisplay.Text + btnOne.Text; } private void btnTwo_Click(object sender, EventArgs e) { txtDisplay.Text = txtDisplay.Text + btnTwo.Text; } private void btnThree_Click(object sender, EventArgs e) { txtDisplay.Text = txtDisplay.Text + btnThree.Text; } private void btnFour_Click(object sender, EventArgs e) { txtDisplay.Text = txtDisplay.Text + btnFour.Text; } private void btnFive_Click(object sender, EventArgs e) { txtDisplay.Text = txtDisplay.Text + btnFive.Text; } private void btnSix_Click(object sender, EventArgs e) { txtDisplay.Text = txtDisplay.Text + btnSix.Text; } private void btnSeven_Click(object sender, EventArgs e) { txtDisplay.Text = txtDisplay.Text + btnSeven.Text; } private void btnEight_Click(object sender, EventArgs e) { txtDisplay.Text = txtDisplay.Text + btnEight.Text; } private void btnNine_Click(object sender, EventArgs e) { txtDisplay.Text = txtDisplay.Text + btnNine.Text; } private void btnZero_Click(object sender, EventArgs e) { txtDisplay.Text = txtDisplay.Text + btnZero.Text; } private void btnClear_Click(object sender, EventArgs e) { txtDisplay.Clear(); } private void btnPlus_Click(object sender, EventArgs e) { total1 = total1 + double.Parse(txtDisplay.Text); txtDisplay.Clear(); plusButtonClicked = true; minusButtonClicked = false; divideButtonClicked = false; multiplyButtonClicked = false; } private void btnEquals_Click(object sender, EventArgs e) { if (plusButtonClicked == true) { total2 = total1 + double.Parse(txtDisplay.Text); } if (multiplyButtonClicked == true) { total2 = total1 * double.Parse(txtDisplay.Text); } else if (minusButtonClicked == true) { total2 = total1 - double.Parse(txtDisplay.Text); } else if (divideButtonClicked == true) { total2 = total1 / double.Parse(txtDisplay.Text); } txtDisplay.Text = total2.ToString(); total1 = 0; } private void btnPoint_Click(object sender, EventArgs e) { txtDisplay.Text = txtDisplay.Text + btnPoint.Text; } bool plusButtonClicked = false; bool minusButtonClicked = false; bool divideButtonClicked = false; bool multiplyButtonClicked = false; private void btnMinus_Click(object sender, EventArgs e) { total1 = total1 + double.Parse(txtDisplay.Text); txtDisplay.Clear(); minusButtonClicked = true; plusButtonClicked = false; divideButtonClicked = false; multiplyButtonClicked = false; } private void btnMultiply_Click(object sender, EventArgs e) { total1 = total1 / double.Parse(txtDisplay.Text); multiplyButtonClicked = true; divideButtonClicked = true; minusButtonClicked = false; plusButtonClicked = false; txtDisplay.Clear(); } private void btnDivide_Click(object sender, EventArgs e) { total1 = total1 / double.Parse(txtDisplay.Text); multiplyButtonClicked = true; divideButtonClicked = true; minusButtonClicked = false; plusButtonClicked = false; txtDisplay.Clear(); } } }