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Module 3: Decimals

Converting from Decimals to Fractions

Tutorial 16: How to Convert for Finite Decimals

Example:

1.65

 

  1. Determine how many digits follow the decimal point (or the place value of the final digit).

    Example: There are two digits that follow the decimal (6 is in the hundredths).

    The denominator of the fraction will be a power of 10 based on how many digits follow the decimal (refer to chart below).

    # of Decimal Digits Example Final Place Value Resulting Denominator
    1 0.1 Tenths 10
    2 0.12 Hundredths 100
    3 0.0123 Thousandths 1000
  2. Build the fraction by placing the decimal portion as the numerator.

    Example: 56 is the decimal portion: 56 100 {"version":"1.1","math":"\dfrac{56}{100}"}

  3. All numbers before the decimal point are whole values, which can be added to the side of the fraction to form a mixed fraction (reduce if possible).

    Example: 1.56: 1 56 100 1 14 25 {"version":"1.1","math":"1\dfrac{56}{100} \rightarrow 1\dfrac{14}{25}"}

  4. Alternatively, consider the whole as part of the numerator and create an improper fraction.

    Example: 1.56: 156 100 {"version":"1.1","math":"\dfrac{156}{100}"}

Tutorial 17: How to Convert for Infinite Decimals

Example:

2.33333…

 

  1. Determine the repeating portion of the decimal.

    Example: 3 repeats constantly: 2.33333…

    The denominator of the fraction will be 9, 99, 999… (etc.) based on how many digits repeat (refer to chart).

    # of Repeating Digits Example Resulting Denominator
    1 0.1 9
    2 0.12 99
    3 0.0123 999
  2. Build the fraction by placing the decimal portion as the numerator.

    Example: 3 is the decimal portion: 3 9 {"version":"1.1","math":"\dfrac{3}{9}"}

  3. Apply the whole portion of the decimal in the same way as for finite fractions and reduce if possible.

    Example: 2.3: 2 3 9 2 1 3 o r 7 3 {"version":"1.1","math":"2\dfrac{3}{9} \rightarrow 2\dfrac{1}{3} or \dfrac{7}{3}"}