### A number is even if it is divisible by 2.

#### The number 90 is even, because it's divisible by 2: the remainder is zero when divided by 2.

#### How to recognize an even number: its last digit, the one that is in the ones place (the first digit of the number counted from the right) is: 0, 2, 4, 6, or 8.

#### Mathematically, the even numbers can be written as:

2 × k, where k ∈ Z, the set of integer numbers

## The number 90 is even.

## Operating rules (scroll down...)

### When working with even and odd numbers, the following rules apply:

#### Addition:

even + even = even; even + odd = odd; odd + odd = even

Examples:

2 + 4 = 6 (even); 1 + 2 = 3 (odd); 1 + 3 = 4 (even).

#### Subtraction:

even - even = even; even - odd = odd; odd - odd = even

Examples:

4 - 2 = 2 (even); 2 - 1 = 1 (odd); 3 - 1 = 2 (even).

#### Multiplying:

even × even = even; even × odd = even; odd × odd = odd

Examples:

2 × 4 = 8 (even); 2 × 3 = 6 (even); 3 × 5 = 15 (odd).