# 4. Arithmetic operators

Arithmetic operators are used with numbers to perform common mathematical operations

Operator

Description

Example

+

x + y

-

Subtraction

x - y

*

Multiplication

x * y

/

Division

x / y

%

Modulus

x % y

//

Floor division

x // y

**

Exponentiation

x ** y

Modulus gives the remainder from a division.
Floor division rounds down the result from a division to the nearest integer.
Exponentiation raises to a power.
```a=9
b=2

print(a + b)
print(a - b)
print(a * b)
print(a / b)
print(a // b)
print(a % b)
print(a ** b)
```
Basic arithmetic operators: `+, -, *, /` are used in the same way as with a calculator.
e.g. converting Celsius to Fahrenheit.
```celsius_temp = 30
fahrenheit_temp = celsius_temp * 9 / 5 + 32
print(fahrenheit_temp)
# 86.0
```
The `%` operator, called `mod` is used to calculate the remainder when one value is divided by another.
For example: finding out if a number is odd or even.
When dividing an integer by 2, the remainder will be 1 for odd numbers and 0 for even numbers.
```number = 3
if number % 2 == 1:
print(f"The number {number} is odd.")
else:
print(f"The number {number} is even.")
```