Factor Calculator

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About the Factor Calculator

The factor calculator finds all the factors of a number. It list all the factor pairs and label the prime factors.

The calculator also tells you how many factors a number has and how many of those factors are prime (so you don't have to count them).

Usage Guide

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i. Valid Inputs

The input needs to be a single integer.

ii. Example

If you would like to see an example of the calculator's working, just click the "example" button.

iii. Solutions

As mentioned earlier, the calculator won't just tell you the answer but also the steps you can follow to do the calculation yourself. The "show/hide solution" button would be available to you after the calculator has processed your input.

iv. Share

We would love to see you share our calculators with your family, friends, or anyone else who might find it useful.

By checking the "include calculation" checkbox, you can share your calculation as well.

Here's a quick overview of what we mean by factors.

What Are Factors?

A factor of a number is an integer that divides into that number evenly (leaves no remainder).

For example, 2\hspace{0.2em} 2 \hspace{0.2em} is a factor of 12\hspace{0.2em} 12 \hspace{0.2em}. Similarly, 3\hspace{0.2em} 3 \hspace{0.2em} is also a factor of 8\hspace{0.2em} 8 \hspace{0.2em}. But 5\hspace{0.2em} 5 \hspace{0.2em} is not a factor of 12\hspace{0.2em} 12 \hspace{0.2em} because it leaves a remainder, 2\hspace{0.2em} 2 \hspace{0.2em}.

Another way to think about factors is as follows.

If two or more integers multiply together to give a product, each of those integers is a factor of the product.

For example —

  • 5\hspace{0.2em} 5 \hspace{0.2em} x 7\hspace{0.2em} 7 \hspace{0.2em} = 35\hspace{0.2em} 35 \hspace{0.2em}. So, both 5\hspace{0.2em} 5 \hspace{0.2em} and 7\hspace{0.2em} 7 \hspace{0.2em} are factors of 35\hspace{0.2em} 35 \hspace{0.2em}.
  • 9\hspace{0.2em} 9 \hspace{0.2em} x 2\hspace{0.2em} 2 \hspace{0.2em} = 18\hspace{0.2em} 18 \hspace{0.2em}. So, both 9\hspace{0.2em} 9 \hspace{0.2em} and 2\hspace{0.2em} 2 \hspace{0.2em} are factors of 18\hspace{0.2em} 18 \hspace{0.2em}.
Are 6\hspace{0.2em} 6 \hspace{0.2em} and/or 4\hspace{0.2em} 4 \hspace{0.2em} factors of 18\hspace{0.2em} 18 \hspace{0.2em}?


If we divide 18\hspace{0.2em} 18 \hspace{0.2em} by 6\hspace{0.2em} 6 \hspace{0.2em}, there are no remainders. So 6\hspace{0.2em} 6 \hspace{0.2em} is a factor of 18\hspace{0.2em} 18 \hspace{0.2em}.

On the other hand, 4\hspace{0.2em} 4 \hspace{0.2em} does not divide into 18\hspace{0.2em} 18 \hspace{0.2em} evenly. There is a remainder of $is not 2 )}. That means 4\hspace{0.2em} 4 \hspace{0.2em} is not a factor of 18\hspace{0.2em} 18 \hspace{0.2em}.

Find all the factors of 72\hspace{0.2em} 72 \hspace{0.2em}.


To find all the factors of a number, we split the number into all possible factors. Here's how.

Step 1.  The first pair would be 1\hspace{0.2em} 1 \hspace{0.2em} times the number itself.

1×721 \hspace{0.25em} \times \hspace{0.25em} 72

Step 2.  For the next pair, we increase the first factor from 1\hspace{0.2em} 1 \hspace{0.2em} to the next smallest factor, in this case, 2\hspace{0.2em} 2 \hspace{0.2em}.

1×722×36\begin{align*} 1 \hspace{0.25em} \times \hspace{0.25em} 72 \\[1em] 2 \hspace{0.25em} \times \hspace{0.25em} 36 \end{align*}

Step 3.  We keep moving ahead with progressively higher factors as long as the seond factor is smaller than or equal to the second factor.

Here's what the list would look like once we have completed the process.

1×722×363×244×186×128×99×8\begin{align*} 1 \hspace{0.25em} &\times \hspace{0.25em} 72 \\[1em] 2 \hspace{0.25em} &\times \hspace{0.25em} 36 \\[1em] 3 \hspace{0.25em} &\times \hspace{0.25em} 24 \\[1em] 4 \hspace{0.25em} &\times \hspace{0.25em} 18 \\[1em] 6 \hspace{0.25em} &\times \hspace{0.25em} 12 \\[1em] {\color{Red} 8} \hspace{0.25em} &\times \hspace{0.25em} {\color{Teal} 9} \\[1em] {\color{Teal} 9} \hspace{0.25em} &\times \hspace{0.25em} {\color{Red} 8} \end{align*}

As you can see, the pairs start repeating as the first factor surpasses the second. So, going ahead would not give us any new factors.

Step 4.  The table (with pairs) above has all the factors we were looking for. So, the factors of 72\hspace{0.2em} 72 \hspace{0.2em} are —

1,2,3,4,6,8,9,and121, \hspace{0.4em} 2, \hspace{0.4em} 3, \hspace{0.4em} 4, \hspace{0.4em} 6, \hspace{0.4em} 8, \hspace{0.4em} 9, \hspace{0.4em} \text{and} \hspace{0.4em} 12

For the negative factors, we place a negative sign before each of the factors above.

Now before we conclude, let me answer a question you might have.

Can Factors Be Negative?

Yes. Technically, factors can also be negative. So factors of 4 would include 1\hspace{0.2em} -1 \hspace{0.2em}, 2\hspace{0.2em} -2 \hspace{0.2em}, and 4\hspace{0.2em} -4 \hspace{0.2em} along with 1\hspace{0.2em} 1 \hspace{0.2em}, 2\hspace{0.2em} 2 \hspace{0.2em}, and 4\hspace{0.2em} 4 \hspace{0.2em}. However, generally, when we say factors, we mean positive factors.

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