Simplest form answer

15/21 Simplified = 5/7

15/21 in simplest form is 5/7, found by dividing 15 and 21 by their greatest common factor, 3. As a decimal 5/7 is 0.7143..., and as a percent it is 71.4286...%.

Simplified

5/7

Decimal

0.7143...

Percent

71.4286...%

Step-by-step GCF reduction

1. Find the greatest common factor.

The GCF of 15 and 21 is 3.

2. Divide the numerator and denominator by the GCF.

15 ÷ 3 = 5

21 ÷ 3 = 7

3. Write the result.

15/21 simplified is 5/7.

Decimal and percentage equivalents

Decimal equivalent

5/7 = 0.7143...

Percentage equivalent

5/7 = 71.4286...%

Visual fraction bar

71.4286...%

The filled part represents 5/7 of one whole.

Cite this result

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15/21 in simplest form is 5/7, found by dividing 15 and 21 by their greatest common factor, 3.
ILoveFractions, https://www.ilovefractions.com/tools/fraction-simplifier/15-21/, retrieved September 2, 2026

APA

ILoveFractions. (2026). 15/21 Simplified = 5/7. ILoveFractions.com. Retrieved September 2, 2026, from https://www.ilovefractions.com/tools/fraction-simplifier/15-21/

MLA

"15/21 Simplified = 5/7." ILoveFractions.com, https://www.ilovefractions.com/tools/fraction-simplifier/15-21/. Accessed 2 September 2026.

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