7th Grade Math

622 Measurement and Proportional Reasoning

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Multiply. Write in simplest form.

1. ^23 × 109 2. 21 × ^67


2. 25 × ^58 4. 4 × _^78


3. 8 × 163 6. ^23 × 9


4. FRUIT A farmer planted 6 acres of
   land with orange trees. During the
   past year, only _^23 of the planted acres
   produced oranges. How many acres
   produced oranges?

EXAMPLE 1

Find _ 43 × _^29.

1 1

2 3

_ 43 × _^29 =

3 × 2

_

4 × 9

Divide 3 and 9 by their GCF, 3. Divide 2 and 4 by their GCF, 2.

= _^16 Simplify.

EXAMPLE 2

Find 5 × _ 103.

1

2

5 × _ 103 =

5

_ 1 × _ 103 Divide 5 and 10 by their GCF, 5.

= ^32 or 1 ^12 Simplify.

Multiply.

8. 5.8 × 10 9. 0.9 × 1,000


9. 1.04 × 100 11. 2.4 × 1,000


10. 0.03 × 100 13. 8.15 × 10


11. MEASUREMENT The height of the
    KVLY Tower in North Dakota in feet
    can be found by multiplying 2.063 by
    1,000. Find the height of the KVLY
    Tower.

EXAMPLE 3

Find 6.3 × 100.

Method 2 Use mental math.

6.3 × 100 = 6.300.

= 630.0 or 630

Method 1 Use paper and pencil.

100

× 6.3

300

6,000

630.0

one decimal place

one decimal place

Move the decimal point

two places to the right.

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