You can do the box trick if…
You cannot subtract the ones place
There is a zero in the tens place
If you can do the box trick, follow these steps:
1.
2.
3.
Put a box around the tens and hundreds.
500
256
Cross it off
500
256
Make it one less
49
500
256
4.
Cross off the ones and carry it up
490
500
256
5.
Add a ten to the ones and subtract
4 9 10
500
256
244