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.
Write this odd number as "double a number plus one". Then say whether your answer is odd or even.
209 = 2 x ______ + 1
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.