Rule of three Calculator

How to Use Our Rule of Three Calculator

Our calculator is designed for ease of use. Input three known values, and let the tool find the missing one. It’s perfect for solving real-world problems like scaling recipes or calculating costs.

Step-by-Step Guide to Calculating Proportions

Follow these steps:

1. Enter the first pair of numbers (e.g., 2 and 4).
2. Input the third known value (e.g., 6).

What Is the Rule of Three in Math?

The rule of three is a simple method to solve proportions. If three values are known in two related ratios, you can find the fourth using cross multiplication.

Examples of Rule of Three Problems

Here are some examples:

• If 3 apples cost $2, how much do 9 apples cost? (Answer: $6)
• If 5 workers finish a job in 10 days, how long will 10 workers take? (Answer: 5 days)

Common Uses of the Rule of Three

It’s used in cooking, budgeting, engineering, and more—anytime you need to scale quantities proportionally.