Arithmetic operators

C# course · Beginner · Lesson 24/116

Learn basic arithmetic with +, -, *, / and %.

Arithmetic operators

In C#, the basic four operations on numbers use arithmetic operators: + for addition, - for subtraction, * for multiplication, / for division. These signs keep the meaning they have in everyday math.

For example, to compute a cafe's daily revenue you would write int revenue = price * cups;. The operator takes two values, produces a new one and assigns it to the variable. Precedence matches school math: multiplication and division first, then addition and subtraction.

Modulo, increment and decrement

Two more operators will come in handy. % (modulo) gives the remainder of a division: 17 % 5 returns 2 because 17 = 3*5 + 2. It is great for even or odd checks.

++ increases a variable by one, -- decreases it by one. count++ is the same as count = count + 1. This shortcut is a lifesaver when you keep a counter.

Exercise Compute the total price

Declare a total variable and assign the product of price and quantity. Then print total with Console.WriteLine. Use the * multiplication operator.

Show example solution

To find the total, write int total = price * quantity; and print it with Console.WriteLine.
Example solution:
using System;

class Program
{
    static void Main()
    {
        int price = 25;
        int quantity = 4;
        // Total price
        int total = price * quantity;
        Console.WriteLine(total);
    }
}

Test yourself

What is the output of Console.WriteLine(6 * 7);?
```
Console.WriteLine(6 * 7);
```
- 36
- 42
- 13
- 67
Show answer

42 — Correct. 6 times 7 is 42.

Write the remainder operator

int remainder = 17 ____ 5;
Console.WriteLine(remainder);

Show answer

int remainder = 17 % 5;
Console.WriteLine(remainder);

Match each operator to its meaning

+

Addition
-

Subtraction
*

Multiplication
/

Division

Arithmetic operators