Is 405 odd or even

Step by step

The question

Question: is 405 odd or even?

Even means it makes pairs, with none left over.

Odd means one is left over.

1 Look at the ones

405 is 400 and 5.

Every ten makes 5 pairs.

So 400 is all pairs.

Only the 5 ones are left to check.

2 Put the ones in pairs

Here are 5 dots in pairs.

A pair is 2.

Ring each pair.

One dot has no partner.

3 Odd or even

One is left over.

So 405 is odd.

4 Check

We count by 2s from 400: 400, 402, 404, 406.

We jump over 405.

405 is not on the list.

Yes!

It works.

Let's look back.

First: look at the ones.

Then: put the ones in pairs.

Then: odd or even.

Last: check.