Numerator
Denominator
=
Numerator
Denominator
Solution
Steps to Solve the Missing Value:
1. Cross-multiply the fractions
2. Simplify and multiply known values
3. Isolate the unknown (x)
How to Solve for an Unknown Fraction
When you have two fractions that are equal to each other (a proportion), but one piece of information is missing, you can use cross-multiplication to find the answer. This calculator is designed to solve for x whether it is in the numerator or the denominator.
To use this tool:
- Enter the three known values into the fraction fields.
- Leave the box you want to solve for blank.
- Click “Solve for Unknown” to see the result and the math used to get there.
The Math Behind Cross-Multiplication
Cross-multiplication is based on the property that if a/b = c/d, then a * d = b * c.
By multiplying the numerator of the first fraction by the denominator of the second, and the denominator of the first by the numerator of the second, you create an equation that allows you to isolate the unknown variable.
Example Problem:
If you have 3/x = 2/3:
- Step 1: Multiply 3 * 3 and x * 2.
- Step 2: You get the equation 9 = 2x.
- Step 3: Divide both sides by 2 to get x = 4.5.