🔀 Proportion Calculator
Solve proportions using cross multiplication
Enter 3 values, leave one empty to solve: a/b = c/d
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How Proportions Are Solved
Formula
a/b = c/d → a × d = b × c
- 1Enter three of the four values in the proportion a/b = c/d.
- 2Leave the unknown value empty.
- 3Cross multiplication is applied: a × d = b × c.
- 4The equation is solved algebraically for the missing value.
- 5The result is verified by checking that both fractions are equal.
About Proportion Calculator
Solve proportions a/b = c/d by finding the missing value. Uses cross multiplication with step-by-step explanation and verification.
Frequently Asked Questions
What is a proportion?
A proportion states that two ratios (fractions) are equal. For example, 1/2 = 3/6 is a proportion.
Why does cross multiplication work?
Cross multiplication works because if a/b = c/d, multiplying both sides by b × d gives a × d = b × c. This eliminates the fractions and creates a simple equation.
Can I solve for any of the four values?
Yes. Leave any one of the four positions empty and the calculator will solve for it.