Elementary Test Prep Math 4 (Grade 3) Estimating Large Numbers

Rounding Numbers

Sometimes you don't need to have an exact number, but a number that is close to the exact number.

Rounding is one way to find a number that's easier to work with.

Use place value to find the place to which a number is rounded.

440 to hundreds	Round	460 to hundreds
440	Find the place value to which you are rounding.	460
440 Leave alone.	If the digit to the right of the place one is rounding to is less than 5, round down ; if it is 5 or greater, round up .	460 Add one.
400	Change the digits to the right to zeros.	500

Examples

	Bob went on vacation. He drove 378 miles the first day and 245 miles the second day. About how many miles did he drive? 378 rounds to 400 245 rounds to 200 400 + 200 = 600 miles
	456 students rode the bus to school today. 422 rode the bus yesterday, and 398 rode the day before. About how many students rode the bus on all three days? 456 rounds to 500 422 rounds to 400 398 rounds to 400 500 + 400 + 400 = 1,300 students

Remember:

When you want to estimate an answer, round
the numbers, and then add or subtract.

Click on the apple for practice.

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