## [Lesson 10] << [Contents] >> [Lesson 12]

The list of Visual Basic 2017 arithmetic l operators are shown in Table 11.1 below:

### Table 11.1 Arithmetic Operators

Operator | Mathematical Function | Example |
---|---|---|

+ | Addition | 1+2=3 |

– | Subtraction | 10-4=6 |

^ | Exponential | 3^2=9 |

* | Multiplication | 5*6=30 |

/ | Division | 21/7=3 |

Mod | Modulus(returns the remainder of an integer division) | 15 Mod 4=3 |

\ | Integer Division(discards the decimal places) | 19/4=4 |

#### Example 11.1

In this program, you insert two text boxes, four labels, and one button. In the properties windows, change the name of the button to BtnCal, the names of text boxes to TxtNum1 and TxtNum2 and change the names of labels to LblSum, LblDiff, LblPdct and LblQuo respectively. Click the button and enter the code window and type the Visual Basic 2017 code as shown below.

Private Sub BtnCal_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnCal.Click Dim num1, num2, difference, product, quotient As Single Dim num1 As Single, num2 As Single Dim sum As Single, diff As Single, pdct As Double, quo As Double num1 = TxtNum1.Text num2 = TxtNum2.Text sum=num1+num2 difference=num1-num2 product = num1 * num2 quotient=num1/num2 LblSum.Text=sum LblDiff.Text=difference LblPdct.Text = product LblQuo.Text = quotient End Sub

Upon running the program, the user may enter two numbers and click on the calculate button to perform the four basic arithmetic operations. The results will be displayed the on the four labels, as shown in Figure 11.1

#### Example 11.2: Pythagoras Theorem

This program involves the use of Pythagoras Theorem to calculate the length of hypotenuse c given the length of the adjacent side a and the length of the opposite side b. In case you have forgotten the formula for the Pythagoras Theorem, it is written as c^2=a^2+b^2 in Visual Basic 2017. In this program, insert two text boxes for the user to enter the value of side a and the value of side b respectively. Add a label to display the result, which is the length of the hypotenuse. Lastly, add a button and change its name to BtnCal and its text to Calculate. Click on the Calculate button and enter the following code.

Private Sub BtnCal_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click 'To draw a triangle at runtime Dim myPen As Pen Dim A As New Point(10, 10) Dim B As New Point(100, 50) Dim C As New Point(60, 150) Dim myPoints As Point() = {A, B, C} myPen = New Pen(Drawing.Color.Blue, 5) Dim myGraphics As Graphics = Me.CreateGraphics myGraphics.DrawPolygon(myPen, myPoints)'Pythagoras equation Dim a1, b1, c1 As Single a1 = TxtA.Text b1 = TxtB.Text c1 = (a1 ^ 2 + b1 ^ 2) ^ (1 / 2) LblC.Text = c1 End Sub

* The first part of the code is to draw a triangle at runtime. You shall learn how to write code to draw a triangle in a later lesson. The output is shown in Figure 11.2

**Figure 11.2**

**Example 11.3: BMI Calculator**

A lot of people are obese now and it could affect their health seriously. Obesity has proven by the medical experts to be one of the main factors that bring many adverse medical problems, including the cardiovascular disease. If your BMI is more than 30, you are considered obese. You can refer to the following range of BMI values for your weight status.

Underweight = <18.5

Normal weight = 18.5-24.9

Overweight = 25-29.9

Obesity = BMI of 30 or greater

BMI can be calculated using the formula weight/( height )^2, where weight is measured in kg and height in meter. If you only know your weight and height in lb and feet, then you need to convert them to the metric system. The code is shown below:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArsgs) Handles Button1.ClickDim height, weight, bmi As Single height = TextBox1.Text weight = TextBox2.Text bmi = (weight) / (height ^ 2) LblBMI.Text = bmi End Sub

The output is shown in the Figure 11.3 below. In this example, height is 1.80m( about 5 foot 11), weight is 75 kg( about 168Ib), and BMI is about 23.14815. The reading suggests that the person is healthy. (Note; 1 foot=0.3048, 1 lb=.45359237 kilogram)

**Figure 11.3**

From the above examples, you can see that writing code that involves arithmetic operations is relatively easy. Here are more arithmetic projects you work on in Visual Basic 2017:

Area of a triangle

Area of a rectangle

Area of a circle

Volume of a cylinder

Volume of a cone

Volume of a sphere

Compound interest

Future value

Mean

Variance

Sum of angles in polygons

Conversion of lb to kg

Conversion of Fahrenheit to Celsius

Conversion of mile to km

Conversion of meter to foot