Bar Model — 9 + 9 = 18 — free printable diagram

What is 9 + 9?

This part-whole bar model shows 9 and 9 as the two parts of one whole. Adding the parts gives the whole, so 9 + 9 = 18.

First part

9

Second part

9

Whole

18

Addition

9 + 9 = 18

Subtraction

18 − 9 = 9

• A part-whole bar model shows the whole on one bar and the parts that make it on the bar underneath. Here the two parts are 9 and 9, and together they fill the whole bar of 18.
• Both parts are the same size, so this is a doubling fact: double 9 is 18.
• Reading it backwards gives the matching halving fact: 18 split into two equal parts is 9 each, so 18 ÷ 2 = 9.
• That is the fact family for these three numbers — the model is the reason 9, 9 and 18 belong together, whichever way round you write them.