3-28 Rounding Numbers

You have exactly 97 stickers and 275 marbles, but you might say that you have about 100 stickers and about 300 marbles.   This is easier than counting all of your marbles or stickers.  When we say we have about 100 stickers and about 300 marbles we used rounding.

To round a number, you look to the right of the place value (or digit) that you want to round.  In the number 27, if you want to round to the nearest ten, you look at the digit 7 in the ones place.

27 rounded to the nearest ten is 30.

In the number 239, if you want to round to the nearest hundred, you look at the digit 3 in the tens place.

239 rounded to the nearest hundred is 200.

REMEMBER: IF THE NUMBER IS 5 OR MORE, ROUND UP.
IF THE NUMBER IS 4 OR LESS, ROUND DOWN.

When you round numbers to the nearest ten, you want to round to the ten that is closest. Begin by looking at the digit to the right of the tens place.  Is it 5 or greater or less than 5?  The answer decides if you round up or down.

Is the number 27 closer to 20 or 30?

The digit 7 in the ones place is 5 or greater so 27 rounds up.

27 is rounded to 30.

When you round numbers to the nearest hundred, you want to round to the hundred that is closest.

Is the number 262 closer to 200 or 300?

The digit 6 in the tens place is 5 or greater so 262 rounds up.

262 is rounded to 300.

When you round numbers to the nearest thousand, you want to round to the thousand that is closest.

Is the number 7,257 closer to 7,000 or 8,000?

The digit 2 in the hundreds place is less than 5 so it does NOT round up.  The number 7,257 is rounded to 7,000.

Round to the nearest ten.

Round to the nearest hundred. 

Round to the nearest thousand.