Simplify 21/27

21/27 simplified is 7/9, after dividing the top and bottom by 3.

Result

Answer

\frac{21}{27} = \textcolor{#0b5c56}{\frac{7}{9}}

21/27 simplifies to 7/9.

  • Greatest common factor: 3
  • Decimal: \displaystyle 0.\overline{7} (the 7 repeats forever, about 0.7778)
  • Percent: 77.78%
21/277/9

Same amount, fewer parts

Step-by-step solution

The problem

\frac{21}{27}

  1. Find the greatest common factor. List the factors of each:
    Factors of 21: 1, 3, 7, 21
    Factors of 27: 1, 3, 9, 27
    The greatest common factor (GCF) is 3.

    \text{GCF}(21, 27) = 3

  2. Divide the top and bottom by 3. Dividing both by the same number keeps the value the same.

    = \frac{21 \div 3}{27 \div 3} = \textcolor{#0b5c56}{\frac{7}{9}}

All the working together

\begin{aligned} &\frac{21}{27} \\[8pt] &= \frac{21 \div 3}{27 \div 3} && \textcolor{#5b6660}{\textsf{divide by 3}} \\[8pt] &= \textcolor{#0b5c56}{\frac{7}{9}}\end{aligned}

21/27 in other forms

Simplest form7/9
Greatest common factor3
Decimal0.777… (the 7 repeats forever)
Percent≈ 77.78%
Equal fractions14/18, 28/36, 35/45, 42/54

Fractions over 27 simplified

FractionSimplest formDecimal
1/27already simplest0.037…
2/27already simplest0.074…
3/271/90.111…
4/27already simplest0.148…
5/27already simplest0.185…
6/272/90.222…
7/27already simplest0.259…
8/27already simplest0.296…
9/271/30.333…
10/27already simplest0.370…
11/27already simplest0.407…
12/274/90.444…
13/27already simplest0.481…
14/27already simplest0.518…
15/275/90.555…
16/27already simplest0.592…
17/27already simplest0.629…
18/272/30.666…
19/27already simplest0.703…
20/27already simplest0.740…
21/277/90.777…
22/27already simplest0.814…
23/27already simplest0.851…
24/278/90.888…
25/27already simplest0.925…
26/27already simplest0.962…

Frequently asked questions

What is 21/27 in simplest form?

21/27 simplifies to 7/9. Divide the top and bottom by 3, their greatest common factor: 21 ÷ 3 = 7 and 27 ÷ 3 = 9.

What is the greatest common factor of 21 and 27?

The GCF of 21 and 27 is 3 – the biggest number that divides both with nothing left over.

Is 21/27 equal to 7/9?

Yes. Both are 0.777… (≈ 77.78%). Simplifying changes how the fraction is written, not its value.

More fractions to simplify

Any other fraction or mixed number: use the Simplify Fractions Calculator.