Review RoundingWrite & Evaluate Expressions

Estimate Sums & Differences

Addition & Subtraction

100,000,000,000 10,000,000,000 1,000,000,000 100,000,000 10,000,000 1,000,000 100,000 10,000 1,000 100 10 1 . .1 .01 .001 .0001 .00001

Hun

dred

Bill

ions

Ten

Bill

ions

One

Bill

ions

Hun

dred

Mill

ions

Ten

Mill

ions

One

Mill

ions

Hun

dred

Tho

usan

ds

Ten

Tho

usan

ds

One

Tho

usan

ds

Hun

dred

s

Ten

s

One

s

Dec

imal

Poi

nt

One

Ten

ths

One

Hun

dred

ths

One

Tho

usan

dths

Ten

Tho

usan

dths

Hun

dred

T

hous

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hs

4 5 9 2 6 1 2 4 0 1 2 5 . 4 6 3 7 8

<--Whole NumbersPart of one (1)->

Equivalent Fraction-> n/10 n/100 n/1000 n/10,000 n/100,000

Find the Place Value and Round

Where do I look first?

• Round this number to the nearest hundred

368

ActionIncrease by one or stays the same

Look at the number to

the right of the action

Use rounding

• When the question asks you to estimate.

Such as:“about how many”…?

When an exact answer isn’t possible. When an answer is difficult to obtain.

(Educated guessing for multiple choice)

Rounding Procedures

1. Draw an arrow pointing to the place you are rounding. (action)

2. Draw a dot (an eye) under the digit to the right of the place you are rounding.

3. If the digit is 0-4, the number with the arrow stays the same. The rest of the numbers to the right change to 0’s.

Rounding Procedures

4. If the digit is 5-9, the number with the arrow rounds up one. The rest of the numbers to the right turn to 0’s.

Rounding Rhyme

• Mark the place,• Look to the right• Four or less are out of sight

• Five and up• Will buy one more,• All those less, are out the door

• In those empty• Right-hand spaces,• Zeros keep the proper places

• Except in places less than a whole • Such as the decimal case • The last number is the last place

5,621

Ut ohhh!

5,621

Oh yea! I’m moving up Wahoo!

6,000

5620

Every place to the right of the arrow changes to zeros

2.88 2.9

No zero place holder for me

Round to the nearest hundreds place.

572,41-4 stay down

5-9 round up one

Answer 4,600

672,4

Answer 4,700

602,4

Answer 4,600

Round 2,593, 672 to the nearest tens place.

672 2,593,

1-4 stay down

5-9 round up one

Answer 2,593,670

Round to the nearest tenth place.

572.4

1-4 stay down

5-9 round up one

600.4Answer

672.4

Answer 4.700

602.4

Answer 4.600

43.27 .5

0549.239 .4

3259.289,5 .3

345,072,749,923 .2

499 .1

Round each number to the place that has an arrow.

500

923,749,100,000

5,289

239.1

30

Practice Rounding

1) 269 (tens)

2) 2.98 (ones)

3) 3,146 (tens)

4) .912 (hundredths)

5) 86,574 (ten thousands)

6) 178.54 (hundreds)

7) 411,990 (hundreds)

Answers

1) 269 (tens)

2) 2.98 (ones)

3) 3,146 (tens)

4) .912 (hundredths)

5) 86,574 (ten thousands)

6) 178.54 (hundreds)

7) 411,990 (hundreds)

3

3,l50

.91

90,000

200.00

270

412,000

Round Numbers

• 64

• 873

• 491

• 652

• 957

• 203

• 684

Answers

• 60• 870 or 900• 490 or 500• 650 or 700• 960 or 1,000• 200• 680 or 700

• 64• 873• 491• 652• 957• 203• 684

Estimate Sums & Differences

• Round off both numbers then add or subtract.

55 + 61 = ?

60 + 60 = 120

691 – 54 = ?

700 – 50 = 650

Math Words

• Place-The position of a digit in a number.

• Value- The product of a digit multiplied by its place.

• Standard Form-The usual way to write a number

• Expanded Form-A way to write a number as a sum of the products of each digit and its place.

• Whole number-any one of the numbers 0, 1, 2, 3, 4, and so on.

Math Words

• Decimal-A number with one or more digits to the right of the decimal point.

• Equivalent decimals- Decimals that name the same number such as .4, .40, .400

• Round-To find the nearest value of a number, based on the given place.

• Estimate-To find a number that is close to the exact answer.

• Variable-A symbol used to represent a number or numbers

Math Words

• Algebraic Expression - A variable by itself or

a combination of one or more variables, one or more operations, and possibly one or more numbers such as

n + 2

• Evaluate or evaluation - To find the value of an expression by performing the operation or operations.

For Examplen = 3, n + 2 3 + 2 = 5

Practice