In this worksheet, we will learn how to express an odd number as "*double a number plus one*" and then identify whether the result is an **odd** or **even** number.

__ For Example__:

**Question:**

Write this odd number as "double a number plus one". Then say whether your answer is odd or even.

209 = 2 x ______ + 1

**Answer:**

If you take one away from 209, you get 208. If you halve this number, you get 104. So

209 = 2 x 104 + 1

which is the same as "double 104 plus one".

The number 104 is an **even** number, since it is divisible by 2.