# Worksheet: Identifying Odd and Even Numbers: Additon Sentences

In this worksheet, we will practice writing expressions of the form a+a or a+a+1 to prove whether a number up to 20 is even or odd.

**Q2: **

Let us think about even numbers. 2, 4, 6, 8, and 10 are examples of even numbers. Notice that they are all doubles.

Which of the following sums has an answer that is an even number?

- A8 + 8
- B8 + 8 + 1

**Q6: **

If a number is **odd**, then we can divide it into two equal groups with one left over.
This means that every odd number can be written as an addition sentence that is a doubles fact plus one.

For example, we know that 11 is odd because .

Which of these addition sentences shows that 9 is odd?

- A
- B
- C
- D