THE "IS"×"OF" and "IS"÷"OF" methods:
Rule:
1. If the word "OF" is between two numbers,
then
A. change the percent on the left of the word "OF"
to a decimal by moving the decimal point two
places left.
B. Multiply by the number on the right of "OF"
2. If the word "IS" is NOT between two numbers,
then
A. If one of them is a percent change it
to a decimal by moving the decimal point two
places left. Otherwise skip this step
B. Divide the "IS" number by the "OF" number.
C. If the question asks for a precent, change the
answer to a percent by moving the decimal two
places to the right and annexing a "%" on the right.
5. find 32% of 600?
The word "OF" is between two numbers, so follow the first rule:
A. change the 32% on the left of the word "OF"
to a decimal by moving the decimal point two
places left, getting .32
B. Multiply .32 by the number on the right of "OF",
which is 600. So .30 x 600 = 180
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6. 14% of what number is 9.8?
The word "OF" is NOT between two numbers, so we use
rule 2.
A. One of them, 14% is a percent, so change it
to a decimal by moving the decimal point two
places left, getting .14
B. Divide the "IS" number, 9.8, by the "OF" number, .14,
getting 70.
C. The question does not ask for a percent, so we skip this step
The answer is 70.
7. what number is 24% of 90?
This is just like problem 5. Change 24% to .24 and multiply by
90, getting 21.6.
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8. 150% of 0.6 is what number?
This is also just like problem 5. Change 150% to 1.5 and multiply
by 0.6, getting .9
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9. 750 is what percent of 150?
the word "OF" is NOT between two numbers,
so we use rule 2:
A. Neither of them is a percent, so we skip this step
B. Divide the "IS" number, 750 by the "OF" number, 150,
getting 5
C. The question asks for a precent, so we change the
answer to a percent by moving the decimal two
places to the right and annexing a "%" on the right.
Since 5 has an invisible decimal on the right we move
it two places right, getting 500, erasing the percent
mark.
Answer: 500%
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10. 48 is 300% of what number?
This is just like problems 6. Change 300% to 3 and divide
the "IS" number 48 by the "OF" number, 3, getting 16.
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11. 2 is what percent of 500?
This is like problem 9.
Divide the "IS" number, 2 by the "OF" number, 500,
getting .004
The question asks for a precent, so we change the
answer to a percent by moving the decimal two
places to the right and annexing a "%" on the right,
getting .4 then annexing a %.
Answer .4%
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12. find 0.5% of 12?
This is just like problem 5. Change 0.5% to .005 and multiply
by 12, getting .06
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13. find 160% of 85?
This is just like problem 5. Change 160% to 1.6 and multiply
by 85, getting 13.6
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14. what number is 265% of 24?
This is just like problem 5. Change 265% to 2.65 and multiply
by 24, getting 63.6
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15. 150 is what percent of 25?
This is like problem 9.
Divide the "IS" number, 150 by the "OF" number, 25,
getting 6
The question asks for a precent, so we change the
answer to a percent by moving the invisible decimal
two places to the right and annexing a "%" on the right,
getting 600 then annexing a %.
Answer 600%
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16. 98 is 5% of what number?
This is just like problems 6. Change 5% to .05 and divide
the "IS" number 98 by the "OF" number, .05, getting 1960.
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17. Marcia bougth $80 in groceries. What is her final cost
after sales tax of 6.5% is added?
Final cost is 100% + 6.5% or 106.5% of $80.
So the question is:
What is 106.5% of $80.
This is just like problem 5. Change 106.5% to 1.065 and multiply
by $80, getting $85.20
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18. Mr. Perez paid 14% of his income in taxes. if his taxes
were $7686, what was his income?
14% of his income is $7686. So the question is
14% of what is $7686.
This is just like problems 6. Change 14% to .14 and divide
the "IS" number $7686 by the "OF" number, .14, getting $54900
Edwin