Directions: Using the digits 1 to 9, at most one time each, fill in the boxes to make the largest (or smallest) absolute difference.

### Hint

What are the biggest and smallest numbers you can make with these digits in scientific notation?

Try thinking of the numbers you create on a number line.

Try thinking of the numbers you create on a number line.

### Answer

Largest: 8×10^9 – 2×10^1

Smallest 1×10^3 – 9×10^2

Smallest 1×10^3 – 9×10^2

Source: Marie Isaac

For smallest difference, one of my classes found the following:

1 x 10^3 – 9 x 10^2

1 x 1000 – 9 x 100

1000 – 900 = 100

Aw, shoot! One of my students came up with one better than the solution for smallest difference, and I was going to email it in, but now I see that someone else (Bob Perez) already found it. She came up with 1 x 10^3 – 9 x 10^2.

Respect to your student for finding it too Amanda!

Thanks for sharing this solution Bob – your class is awesome to have found it. I’ve updated the answer to reflect this – do let them know!