Rule of Three

If 4 pencils cost 8 coins, how much do 6 pencils cost? This application was developed to facilitate and speed up the calculation of the Rule of Three, as well as to expand your knowledge about this important mathematical tool. Rule of Three (Top), Multiple languages, Light theme, Dark theme, Detailed help, Completely free, No data collection, No advertisements, No permissions.

The rule of three is a very useful mathematical technique that allows you to solve problems involving proportions between quantities. It is used to find an unknown value from three known values that are proportionally related. The rule of three is a specific application of cross-multiplication to solve proportions.

Example 1: If 4 pencils cost 8 coins, how much do 6 pencils cost?
Using the app, enter the values ​​of A, B and C in this way:
pencils coins
A = 4 C = 8
B = 6 X = ?
Tap the Calculate button
The app will show X = 12
That is, 6 pencils cost 12 coins.

Example 2: A painter takes 8 days to paint a house working 6 hours a day. If he starts working 12 hours a day, in how many days will he finish the job?
Using the app, enter the values ​​of A, B and C in this way:
hours days
A = 6 C = 8
B = 12 X = ?
Check the option: Inversely proportional
Tap the Calculate button
The app will show X = 4
If he works 12 hours a day, he will finish in 4 days.