About this tool
Most number questions are one of a handful: what is 15% of a price, how much a discount takes off, if 2 kg cost 10 how much do 5 kg cost, what are the roots of x² − 5x + 6 = 0, or what is the GCD and LCM of a few numbers. Here those four calculators live together: percentage (X% of Y, what percentage, change, discount and tip), rule of three (direct and inverse), quadratic equations by Bhaskara with the parabola, and GCD and LCM with the prime factorization and Euclid's steps. Choose what you want to calculate at the top. Each tab shows how the answer was found, keeps what you typed while the page is open, and everything is worked out in your browser: nothing is sent to a server or kept in the address.
How to use it
- 1 Choose at the top what you want to calculate: percentage, rule of three, quadratic equation, or GCD and LCM.
- 2 Type the numbers, or tap one of the examples.
- 3 Read the answer and the steps below it, and copy a link if you want to share the calculation.
- 4 Switch tabs at any time: each calculator keeps what you typed while the page is open.
Frequently asked questions
Are the numbers I type saved or sent anywhere?
No. They stay in your browser. They are not sent to a server, not saved and not kept in the page address; only the link you choose to copy carries them.
Do the old calculator pages still exist?
Yes. Percentage, rule of three, quadratic equation and GCD and LCM each keep their page, which opens this same box on its own tab.
Where are the unit converter and the grade average?
The converters have their own page, because you type a value with its unit there. The grade average is now with the education tools.
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