500
3425 and 1762
39.3264
8 and 4 have a difference of 4.
22333332
16
An estimated difference is when you can't be bothered to calculate the exact number, so you simplify things a bit. An estimate for 800-something - 400-something would be 400.
1306
100-99=1
it can help you determine whether toy made an error in calculating an exact sum or difference.
301 ad 1
Please provide more context or details so I can give you an accurate answer.