Rounding Decimal Numbers

Grade 6 Unit NSN

Re-cap… What is a place value chart? What are the periods in the place value

chart? What are the greater than and less than

symbols?

What does it mean to round a number?

What does it mean to estimate?

Molly has $16 in her pocket

She buys:

•3 hotdogs @ $1.89 each

•3 milkshakes @ $2.19 each

•3 Large French fries @ $ $1.79 each

Does she have enough money?

Gas costs $1.79 per gallon

I’m running on empty and I have a 20 gallon tank on my truck……

About how much will it cost to fill up?

You have one hour to take a 50 question test.

About how much time can you spend on each question?

The Rounding Poem

Find your number

Look right next door

4 or less, just ignore

5 or more add one more!

Rounding Whole Numbers

Round 474 to the closest hundred.

474 Find your numberLook right next door

Four or less, just ignore

Five or more, add one more

474 Rounded to the hundreds becomes 500

Round 474 to the closest 10’s

474

Just ignore - 470

Try These•4,215

•394

•27

•127,591

•638

What about decimal numbers

The same rules (and poem) apply!Round 4.167 to the closest hundredths

4.167 Find your number

Look right next door

4.17

RememberIf you are asked to round to the nearest tenth…….your

answer stops at the tenth place!

Example: Round 42.73 to the closest tenth would be 42.7

Special Case!Rounding a 9

Round 2.197 to the closes hundredths

Since there is a “9” in the hundredths place consider the tenth and hundredths together – 19 – do you leave it at 19 or move it to 20?

Round 4.95 to the closest tenth

Since there is a “9” in the tenth spot consider the ones and tenths together…… should you leave it at 49 or move it to 50?

4.95 rounded to the nearest tenth is 5.0

Try these

Round to tenths:

4.56 4.6

5.32 5.3

0.98 1.0

Round to hundredths

18.784 18.78

9.456 9.46

9.997 10.00