Odd, even, and the one left over
A number sits in the middle of the screen and you tap Odd or Even to sort it. The idea behind the two words is simple to picture: an even number can be shared into two equal groups with nothing spare, like 2, 4 or 10, while an odd number always leaves one over however you split it, like 1, 3 or 7. A right tap scores and moves on, a wrong one shows the correct answer, and a round is ten numbers with your best score kept. Start on To 20, then step up to To 100.
Just look at the last digit
You never have to look at the whole number, only its last digit. If it ends in 0, 2, 4, 6 or 8 the number is even; if it ends in 1, 3, 5, 7 or 9 it is odd. That is the entire rule, and the wonderful thing is that it holds no matter how huge the number gets, so 3,458 is even for exactly the same reason 8 is. Once a child trusts the last digit, even the To 100 round takes no longer than the small numbers.
Where odd and even turn up later
Odd and even is a child first taste of the idea that numbers have properties, not just sizes, and it quietly opens the door to sharing fairly, to the two times table, and later to division and remainders. The last-digit rule they pick up here is a genuine keeper, the kind of shortcut they will still lean on years later when checking whether a number divides evenly. It is a small idea that keeps paying off.
Frequently asked questions
How do you play Odd or Even?
A number appears on the screen. Decide whether it is odd or even, then tap the Odd button or the Even button. Answer 10 numbers and see your score.
How do you tell if a number is odd or even?
Look at the last digit. If it ends in 0, 2, 4, 6 or 8 the number is even. If it ends in 1, 3, 5, 7 or 9 the number is odd. Even numbers can be shared into two equal groups.
Is zero odd or even?
Zero is even. It ends in 0, and it can be split into two equal groups of nothing with none left over, which is exactly what makes a number even. Children often assume it is a special case, so it is a good one to point out and clears up a common mix-up.