© 2007 M. Tallman. Find your number. Look right next door. 35 Step 1: Circle the digit in the place...

transcript

Find your number.Look right next door.

Step 1: Circle the digit in the place that you must round to.

Step 2: Draw an arrow to the place on the right.

Round to the nearest thousands place.

000346

Step 3: If the number is four or less, then the circled number stays the same.

Step 4: All numbers to the right of the circled number become zeros.

4 or less, just ignore.

3 is less

than 4

Just Ignore!

Round to the nearest thousands place.

Find your number.

Round to the nearest hundreds place.

Look right next door.

006765

4 or less, just ignore.5 or more, add 1 more.

7 is not less than

Step 3: If the number is four or less, then the circled number stays the same.

Step 4: If the number is 5 or greater, then add 1 to the circled number.

Step 5: All numbers to the right of the circled number become zeros.

Round to the nearest hundreds place.

5 + 1 = 6

When to use estimation…

When an exact answer is not needed.

When you need to compute a problem quickly.

To check your work.

486 + 130

5 1+ = 6Step 1: Rounding is always first. Decide which place to round to.

Step 2: Round each addend to the hundreds place.

00000 0

The actual answer is 616,

so our estimation is

pretty accurate.

The actual answer is 616,

so our estimation is

pretty accurate.

Step 3: Now you can add 500 and 100 mentally.

5,387 + 386

5,000 400+ =5,400

Step 1: Rounding is always first. Decide which place to round to.

Step 2: Round the first addend to the thousands place and the second addend to the hundreds place.

Step 3: Now you can add 5,000 and 400 mentally.

The actual answer is 5,773, so our estimation is pretty

accurate

Rounding Tip: The lower the place, the more accurate the answer. However, if you round too low, your problem may be more difficult to solve.

Rounding Tip: The higher the place, the easier your problem will be to solve. However, your answer may not be as accurate.

5,387 + 386

5,000 400+ =5,400

Step 1: Rounding is always first. Decide which place to round to.

Step 3: Now you can add 5,400 and 400 mentally.

Step 2: Round the first addend to the thousands place and the second addend to the hundreds place.

44,897 + 26,578

40,000 30,000+ =70,000Step 1: Rounding is always first. Decide which place to round to.

Step 2: Round each addend to the ten thousands place.

Step 3: Now you can add 40,000 and 30,000 mentally.

The actual answer is

71,475, so our estimation is

pretty accurate.

71,475, so our estimation is

pretty accurate.

$8.67 + $6.75

$9.00 $7.00+ =$16.00Step 1: Rounding is always first. Decide which place to round to.

Step 2: Round each addend to the nearest dollar.

Step 3: Now you can add $9.00 and $7.00, mentally.

$15.42, so our estimation is

pretty accurate.

$15.42, so our estimation is

pretty accurate.

1. $21.89 + $6.78

600100+500=

1,200500 +700 =

$27.00

4. 4,897 + 598

3. 145 + 467

Estimate Each Sum

2. 467 + 721

$20.00+$7.00=

5,600+600 =

5. 897,965 + 12,854

800,000

10,0006,000+4,000=

$350.00$50.00+$300.00=

910,000

8. 765,987 + 46,980

7. 5,897 + 4,465

Estimate Each Sum

6. $47.90 + $271.87

900,000+10,000=

850,000+50,000=

9. $8.75 + $3.98

200,000

38,0008,000+30,000=

$900.00$400.00+$500.00=

$13.00

12. 167,876 + 446,987

11. 8,321 + 32,432

Estimate Each Sum

10. $376.98 + $547.98

$9.00+$4.00 =

600,000+400,000=

© 2007 M. Tallman. Find your number. Look right next door. 35 Step 1: Circle the digit in the place...

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