Simplify 7/21

7/21 simplified is 1/3, after dividing the top and bottom by 7.

Result

Answer

\frac{7}{21} = \textcolor{#0b5c56}{\frac{1}{3}}

7/21 simplifies to 1/3.

  • Greatest common factor: 7
  • Decimal: \displaystyle 0.\overline{3} (the 3 repeats forever, about 0.3333)
  • Percent: 33.33%
7/211/3

Same amount, fewer parts

Step-by-step solution

The problem

\frac{7}{21}

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

    \text{GCF}(7, 21) = 7

  2. Divide the top and bottom by 7. Dividing both by the same number keeps the value the same.

    = \frac{7 \div 7}{21 \div 7} = \textcolor{#0b5c56}{\frac{1}{3}}

All the working together

\begin{aligned} &\frac{7}{21} \\[8pt] &= \frac{7 \div 7}{21 \div 7} && \textcolor{#5b6660}{\textsf{divide by 7}} \\[8pt] &= \textcolor{#0b5c56}{\frac{1}{3}}\end{aligned}

7/21 in other forms

Simplest form1/3
Greatest common factor7
Decimal0.333… (the 3 repeats forever)
Percent≈ 33.33%
Equal fractions2/6, 3/9, 4/12, 5/15

Fractions over 21 simplified

FractionSimplest formDecimal
1/21already simplest0.047619…
2/21already simplest0.095238…
3/211/70.142857…
4/21already simplest0.190476…
5/21already simplest0.238095…
6/212/70.285714…
7/211/30.333…
8/21already simplest0.380952…
9/213/70.428571…
10/21already simplest0.476190…
11/21already simplest0.523809…
12/214/70.571428…
13/21already simplest0.619047…
14/212/30.666…
15/215/70.714285…
16/21already simplest0.761904…
17/21already simplest0.809523…
18/216/70.857142…
19/21already simplest0.904761…
20/21already simplest0.952380…

Frequently asked questions

What is 7/21 in simplest form?

7/21 simplifies to 1/3. Divide the top and bottom by 7, their greatest common factor: 7 ÷ 7 = 1 and 21 ÷ 7 = 3.

What is the greatest common factor of 7 and 21?

The GCF of 7 and 21 is 7 – the biggest number that divides both with nothing left over.

Is 7/21 equal to 1/3?

Yes. Both are 0.333… (≈ 33.33%). 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.