# Visual Basic 2008 Tutorial

## Lesson 7: Mathematical Operations

Computer can perform mathematical calculations much
faster than human beings. However, computer itself cannot perform
any mathematical calculations without receiving instructions from the user. In
VB2008, we can write code to instruct the computer to perform mathematical
calculations such as addition, subtraction, multiplication, division and other
kinds of arithmetic operations. In order for VB2008 to carry out arithmetic
calculations, we need to write code that involve the use of various arithmetic
operators. The VB2008 arithmetic operators are very similar to the normal
arithmetic operators, only with slight variations. The plus and minus operators
are the same while the multiplication operator use the * symbol and the division
operator use the / symbol.

The list of VB2008 arithmetic operators are shown in
table 7.1 :

**
Table 7.1: Arithmetic Operators**

**
Operator** |
**
Mathematical function** |
**
Example** |

+ |
Addition |
1+2=3 |

-- |
Subtraction |
4-1=3 |

^ |
Exponential |
2^4=16 |

* |
Multiplication |
4*3=12,
(5*6))2=60 |

/ |
Division |
12/4=3 |

Mod |
Modulus (return the
remainder from an integer division) |
15 Mod 4=3
255 mod 10=5 |

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

### Example 7.1

In this program, you need to insert two text boxes, four labels and one button. Click the button and enter the code as shown below. When you run the program,
it will perform the four basic arithmetic operations and display the results on
the four labels.

Private Sub
Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
Handles Button1.Click

Dim sum, num1, num2, difference, product, quotient As Single

num1 = TextBox1.Text

num2 = TextBox2.Text

sum=num1+num2

difference=num1-num2

product = num1 * num2

quotient=num1/num2

Label1.Text=sum

Label2.Text=difference

Label3.Text = product

Label4.Text = quotient

End Sub

**Example 7.2**

The program can use Pythagoras Theorem to calculate the
length of hypotenuse c given the length of the adjacent side a and 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**

Private Sub
Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
Handles Button1.Click

Dim a, b, c As Single

a = TextBox1.Text

b = TextBox2.Text

c=(a^2+b^2)^(1/2)

Label3.Text=c

End Sub

**Example 7.3: 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 causes of various medical
problems, including the heart disease and diabetics. If a person BMI is more than 30, he or she can be 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 could just use a calculator or a
home made computer program, this is exactly what I am showing you here. The BMI
calculator is a Visual Basic 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 (you could indeed write a VB program for the
conversion).

Private Sub
Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
Handles Button1.Click

Dim height,
weight, bmi As Single

height = TextBox1.Text

weight = TextBox2.Text

bmi = (weight) / (height ^ 2)

Label4.Text = bmi

End Sub

The output is shown in the
diagram below. In this example, your height is 1.80m( about 5 foot 11),your
weight is 78 kg( about 170 Ib), and your BMI is found to be 23.5. The reading suggests
that you are healthy. (Note; 1 foot=0.3048, 1 lb=.45359237
kilogram)

From the above examples, you can see that performing
arithmetic operations is relatively easy in VB2008. Here are more arithmetic projects you
can try to programs:

- 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

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