Rule of Three
Solve proportions using the simple rule of three.
If... then...
How to calculate the Simple Rule of Three?
A Simple Rule of ThreeIt is one of the most used methods in basic mathematics to find an unknown value when we already know three other values that form a proportion.
Practical example of daily life
Imagine that you are at the market and see that 2 kg of meat costs R$ 60, but you want to buy 5 kg and need to know how much it will cost.
- Step 1:Align the quantities. (2 kg corresponds to R$ 60).
- Step 2:Define what you want to find out. (5 kg are for X).
- Step 3:Cross multiply (2 * X = 5 * 60). Where X = 300 / 2 = R$ 150.
With our online calculator, you don't need to do any calculations on paper. Just enter the three values you know, and we will find the \"X\" for you instantly.
Directly proportional quantities
This calculator is set up to solve problemsdirectly proportional, which cover 99% of common needs (such as converting recipes, calculating fuel expenses, finding yields, etc). That is, if one value increases, the other value associated with it must also increase in the same proportion.