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.
3425 and 1762
it can help you determine whether toy made an error in calculating an exact sum or difference.
301 ad 1
None of the digits need be estimated.
The last digit is always the estimated digit in a number
500
3425 and 1762
39.3264
8 and 4 have a difference of 4.
16
22333332
1306
1306
100-99=1
it can help you determine whether toy made an error in calculating an exact sum or difference.
Please provide more context or details so I can give you an accurate answer.
(A) Add them together.(B) Subtract the smaller from the larger.