Addition Strategy: Near Doubles

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What is a 'near doubles' fact?

It's an addition problem where the two numbers are neighbors, meaning they are just one number apart (like $4+5$ or $6+7$).

How can you use the doubles fact $3+3=6$ to help you solve $3+4$?

You know $3+3=6$. Since $4$ is just one more than $3$, the answer is one more than $6$. So, $3+4=7$.

Use a doubles fact to solve: $4 + 5 = ?$

Think: $4+4=8$. Then add one more. So, $4+5=9$.

Use a doubles fact to solve: $5 + 6 = ?$

Think: $5+5=10$. Then add one more. So, $5+6=11$.

Use a doubles fact to solve: $6 + 7 = ?$

Think: $6+6=12$. Then add one more. So, $6+7=13$.

Use a doubles fact to solve: $7 + 8 = ?$

Think: $7+7=14$. Then add one more. So, $7+8=15$.

Use a doubles fact to solve: $8 + 9 = ?$

Think: $8+8=16$. Then add one more. So, $8+9=17$.

Let's try another way. To solve $4+5$, can you use $5+5$?

Yes. Think: $5+5=10$. Since $4$ is one less than $5$, the answer is one less than $10$. So, $4+5=9$.

$$ 2 + 3 = ? $$

Think $2+2=4$, so $2+3=5$.

$$ 3 + 2 = ? $$

Think $2+2=4$, so $3+2=5$. (This is also a turn-around fact!)

$$ 8 + 7 = ? $$

Think $7+7=14$, so $8+7=15$.