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Is 99 odd or even

Step by step, with the reason for every step · Odd and even · Elementary

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

Your turn

Try this one yourself, then check:

Is 103 odd or even?
Show the answer
odd

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