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 .