AI Tutor
Imagine you have 7 red toy cars and 8 blue toy cars in a row.
You already know that 7+7=147 + 7 = 14. How fast can you figure out 7+87 + 8 without counting by ones?

The Doubles Plus One Trick

A near double is an addition fact where two numbers are right next to each other on the number line, like 7 and 8.
Because 8 is just 7+17 + 1, you can double the smaller number first: 7+7=147 + 7 = 14, and then add 1 more to get 15.
That makes 7+8=157 + 8 = 15 super fast! But what if your brain prefers looking at the bigger number first?

The Doubles Minus One Trick

You can also use the larger number's double and take 1 away.
Let's solve 8+98 + 9. If both numbers were 9, you would have 9+9=189 + 9 = 18.
Since 8 is 1 less than 9, just subtract 1 from 18: 18−1=1718 - 1 = 17.

Watch Out for the Switch