# Greatest Difference of Two Rounded Numbers

Directions: Using the digits 0 through 9, find two numbers that round to 500, and have the greatest possible difference. Each digit can only be used once.

### Hint

How can we figure out the greatest number that rounds to 500?
What tools or models might be helpful?
What does the “greatest possible difference” mean?
Can you make a bigger difference than what you have now?

539 – 460 = 79

Source: Michael Wiernicki, Graham Fletcher, and Rachel Nelli.

## Multiply and Divide Within A Hundred 1

Directions: Using the digits 2 to 9 at most one time each, place a digit …

1. I’m trying to understand the wording in this one. It reads as though students are supposed to round two numbers to 500 and then subtract. This makes no sense because the greatest possible difference when subtracting 500 from 500 is going to be 0.
So I knew the problem as written made no sense but I didn’t know what was being asked.
How about “Using the digits 0 through 9, find two numbers that round to 500, and have the greatest possible difference. Each digit can only be used once.”

The correct answer is 539 – 461 = 78

3. Miss Hamer & 3/4H

We found 539-460 = 79
XD