Estimating differences means finding an approximate answer to a subtraction problem by rounding numbers before subtracting.
Estimating helps you check if your exact answer is reasonable. It's like making a good guess before finding the precise answer.
To round to the nearest ten, look at the ones digit. If it's 5 or greater, round up. If it's 4 or less, round down.
When rounding to the nearest ten, the number will always end with a zero.
To round to the nearest hundred, look at the tens digit. If it's 5 or greater, round up. If it's 4 or less, round down.
When rounding to the nearest hundred, the number will always end with two zeros.
Round both numbers to the nearest ten, then subtract to find the estimated difference.
This method gives you a closer estimate than rounding to the nearest hundred.
Round both numbers to the nearest hundred, then subtract to find the estimated difference.
This method is faster but gives a less precise estimate than rounding to the nearest ten.
Estimation is helpful when you need a quick answer or want to check if your exact calculation is reasonable.
Always estimate before calculating exactly. If your exact answer is very different from your estimate, check your work!