Comparing quantities and solving for unknowns
A ratio compares two quantities. 3:4 means for every 3 of one thing there are 4 of another. A proportion states that two ratios are equal: a/b = c/d. Cross multiplication: To solve a/b = c/d for an unknown, cross multiply: a×d = b×c. Example: 3/4 = x/20 → 3×20 = 4×x → 60 = 4x → x = 15. Real-world uses: Scaling recipes (double a recipe), map scale (1:50,000 means 1cm = 500m), currency exchange, mixing solutions (2 parts paint to 1 part thinner), speed calculations, and unit price comparisons. Simplifying ratios: Divide both terms by their GCD. 12:18 → GCD is 6 → 2:3. This is like simplifying fractions. Percent as ratio: 25% = 25:100 = 1:4. Percentages are ratios with 100 as the denominator, which is why ratio and percentage calculations are closely related.
Other useful tools related to mathematical calculations
Enter 3 values to find the unknown (a/b = c/d)
How to Use? To simplify a ratio, enter two numbers. To solve proportion, enter three of four values, unknown will be calculated.
Reduce ratios to simplest form: 12:8 = 3:2
Find unknown in a/b = c/d equation
Automatic simplification using Greatest Common Divisor
Cross multiplication method for proportions
About ratios and proportions
Comparison of two or more quantities. Example: 12:8 or 3/2