### How do you know this is odd number or even?

even numbers start with 2 4 6 8 10 they are even if you can count them in 2 or divide them by two odd numbers start with 1 3 5 7 8 11 the cannot be counted by two or divided equally 21 starts with 2 and isn't even. 12 starts with 1 and isn't odd. An even number is a whole number ("a counting number" ) which ends with 0, 2, 4, 6…