Remind your child about odd and even numbers. Can they tell you why a number is odd or even?
An even number is a number that can be divided into two equal groups. An odd number is a number that cannot be divided into two equal groups. Even numbers end in 2, 4, 6, 8 and 0 regardless of how many digits they have (we know the number 5,917,624 is even because it ends in a 4!). Odd numbers end in 1, 3, 5, 7, 9.
Use the 100 splat to splat even numbers then clear it and do the same with odd numbers. What do they notice?