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

### Table 11.1: Arithmatic 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 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 2015 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 SingleDim num1 As Single, num2 As Single, 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 2015. 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 it 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 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 a one of the main factors that brings many adverse medical problems, including the 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

In order to calculate your BMI, you do not have to consult your doctor, you can simply use a calculator or a home made computer program, this is exactly what I am showing you here. This BMI calculator is a Visual Basic 2015 program that can calculate the body mass index, or BMI of a person based on the body weight in kilogram and the body height in meter. 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:

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, your height is 1.80m( about 5 foot 11),your weight is 75 kg( about 168Ib), and your BMI is about 23.14815. The reading suggests that you are healthy. (Note; 1 foot=0.3048, 1 lb=.45359237 kilogram)

**Figure 11.3**

From the above examples, you can see that writing code that involve arithmetic operations is relatively easy. Here are more arithmetic projects you work on in Visual Basic 2015:

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 metre to foot