Step by step
The question
Question: is 99 odd or even?
Is 99 odd or even?
Even means it makes pairs, with none left over.
Odd means one is left over.
even: all in pairs
odd: 1 left over
1 Look at the ones
99 is 90 and 9.
99 = 90 + 9
Every ten makes 5 pairs.
So 90 is all pairs.
Only the 9 ones are left to check.
10 = 5 pairs
2 Put the ones in pairs
Here are 9 dots in pairs.
A pair is 2.
Ring each pair.
One dot has no partner.
3 Odd or even
One is left over.
So 99 is odd.
= 99 is odd
4 Check
We count by 2s from 90: 90, 92, 94, 96, 98, 100.
We jump over 99.
99 is not on the list.
Yes!
It works.
90, 92, 94, 96, 98, 100
Let's look back.
First: look at the ones.
Then: put the ones in pairs.
Then: odd or even.
Last: check.
Answer
= 99 is odd