Even and odd numbers

An even number can be split into pairs with none left over; an odd number always has one left over. The quick rule: even numbers end in 0, 2, 4, 6 or 8, and odd numbers end in 1, 3, 5, 7 or 9. This page shows why with a pairs tool, what happens when you add evens and odds, and whether 0 is even.

Even and odd: the pairs idea

Put objects in pairs, like socks. If every object has a partner, the number is even. If one is left alone, it is odd. Even numbers can also be split into two equal groups (2.OA.C.3): 12 = 6 + 6, but 13 can’t.

The last digit rule

Only the ones digit matters, because every ten splits into pairs. 347 ends in 7, so it is odd. 1,000,002 ends in 2, so it is even, however big it is.

Adding even and odd numbers

Is 0 even or odd?

0 is even. Zero objects leave nobody without a partner, and 0 sits between −1 and 1, which are both odd. On the number line, evens and odds alternate, so 0 must be even.

Common mistakes

How to teach it at home

Sock pairs

Pair up socks from the laundry. Any odd one out?

House numbers

Odd numbers are usually on one side of the street, even on the other.

Card game

Flip a card: even, clap; odd, stamp.

By grade

• Grade 2 (2.OA.C.3): decide whether a group up to 20 is odd or even by pairing or counting by 2s, and write even numbers as a sum of two equal addends.
• Next: skip counting.

Worksheets and practice

Even and odd numbers worksheet: printable PDF with an answer key. · Make a fresh test

Odd and even numbers chart · Number sense