Directions: Use the digits 1 to 9, at most one time each, to fill in the boxes to create a true number sentence with the greatest possible value.

### Hint

### Hint

How do we know if both sides of the equal sign have the same value?

What is the greatest possible value each side of the equal sign can have?

### Answer

### Answer

2 + 6 = 9 – 1

6 + 2 = 9 – 1

3 + 5 = 9 – 1

5 + 3 = 9 – 1

4 + 4 = 9 – 1 is not an answer because the 4 is used twice.

There might also be conversations about whether 2 + 6 = 1 – 9 is an answer. This may lead into conversations about how addition is commutative (1 + 4 equals 4 + 1) but subtraction is not (1 – 4 does not equal 4 – 1).

What students MIGHT think is correct, but is NOT correct is something like:

4 + 5 = 9 – (any number other than 0)

This would be because 4 + 5 = 9. However, both sides of the equal sign must have the same value, and they do not when you subtract another number other than zero.

Source: Robert Kaplinsky