How do you use rounding to check if answers are reasonable?

Rounding can help determine if an answer is reasonable by simplifying the numbers involved to make mental calculations easier. For instance, if you round numbers to the nearest ten or hundred, you can quickly estimate what the result should be. After performing the exact calculation, you can compare the result to your rounded estimate; if the answer is significantly different, it may indicate an error in the calculation. This method serves as a quick check to validate the plausibility of the solution.