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.