Fractions, Percents, and Decimals
Sevens
Notice that the fractional part of the mixed number percent
for the sevens fractions for a pattern. Simply multiply the
numerator by 2. If the product is greater than 7, then subtract 7
from the product.
Example:
Nines
With fractions of nines, simply multiply the numerator times
11 for the whole number part of the mixed number percent and tack
on the original fraction.
Example:
Elevens
With fractions of elevens, simply multiply the numerator times
9 for the whole number part of the mixed number percent and tack
on the original fraction.
Example:
Converting between fractions, decimals, and percents
Fractions to Decimals
To convert from fractions to decimals, divide the numerator by
the denominator until you reach a remainder of zero.
Example:
Decimals to Fractions
To convert from decimals to fractions, think of the decimal as
a whole number by dropping the decimal point. Then divide this
number by a power of 10, using the same number of zeroes after
the 1 as the number of places after the decimal point.
Example:
Change .15 to 15, and place it in a fraction over 100. We use
100 because it has two zeroes, the same number as the number of
places after the decimal in .15. Then, reduce the fraction.
Decimals and Percents
To convert from decimals to percents, multiply by 100. This is
also the same as moving the decimal two places to the right. To
convert from percents to decimals, divide by 100. This is also
the same as moving the decimal two places to the left.
Example:
 (Move the decimal two places to the
right.)
Advanced Tricks for Middle School and High School Students
There are several advanced tricks involving special types of
fraction to decimal problems.
- If the fraction has a denominator of 20, simply multiply
the numerator by 5 and use two decimal places.
- If the fraction has a denominator of 25, simply multiply
the numerator by 4 and use two decimal places. Note:
Sometimes, the denominator is written as
 .
- If the fraction has a denominator of 40, simply multiply
the numerator by 25 and use three decimal places,
depending on the number. You can use the Multiplication
by 25 trick with this type of problem.
- If the fraction has a denominator of 50, simply multiply
the numerator by 2 and use two decimal places.
- If the fraction has a denominator of 80, simply multiply
the numerator by 125 and use four decimal places. You can
use the Multiplication by 125 trick with this type of
problem.
- If the fraction has a denomiator of 125, simply multiply
the numerator by 8 and use three decimal places. Note:
Sometimes, the denominator is written as
 .
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