Estimating Sums and Differences

Front

What is estimating sums?

Back

Estimating sums means finding a close value to the actual sum of two or more numbers by rounding them to the nearest ten, hundred, or other place value.

Front

What is estimating differences?

Back

Estimating differences involves finding a close value to the actual difference between two numbers by rounding them to the nearest ten, hundred, or other place value.

Front

How do you round a number to the nearest ten?

Back

To round a number to the nearest ten, look at the digit in the ones place. If it is 5 or more, round up. If it is 4 or less, round down.

Front

What is the estimated sum of 243 and 333 when rounded to the nearest hundred?

Back

The estimated sum is 600 (200 + 300).

Front

What is the estimated difference between 333 and 243 when rounded to the nearest ten?

Back

The estimated difference is 100 (330 - 240).

Front

If Becca counted 148 red cars and 153 blue cars, what is the estimated total when rounded to the nearest ten?

Back

The estimated total is 300 (150 + 150).

Front

What is a reasonable estimate for the total cost of a shirt for $17 and pants for $29?

Back

The estimated total cost is $50 (20 + 30).

Front

How do you determine if you have enough money to buy items?

Back

Add the prices of the items and compare the total to the amount of money you have.

Front

What is the estimated total number of works of art on three floors with 237, 349, and 219 works?

Back

The estimated total is 700 (200 + 300 + 200).

Front

If Jill took 32 minutes for math and 16 minutes for reading, what is the estimated total time spent?

Back

The estimated total time is 50 minutes (30 + 20).