数学
パーセンテージ、分数、べき乗などの数学計算。
6種類の計算機
数学
Percentage Calculator
Percentages are everywhere: discounts, interest, VAT and grades. This calculator answers the three most common percentage questions in a single click: how much is X% of Y, what percentage X is of Y, and how much something increased or decreased in percent.
Proportion Calculator
A proportion like A/B = C/X shows up everywhere: scale drawings, recipes you want to scale, mixing ratios and unit conversions. Enter A, B and C and this calculator instantly finds the missing fourth term X, showing the cross-multiplication steps.
RREF Calculator (Matrix)
Enter the coefficients of a system of three linear equations in three unknowns (x, y, z). The calculator reduces the associated matrix step by step to reduced row echelon form (RREF) using Gauss-Jordan elimination and reads off the solution.
Percentile Calculator (Z-score)
A percentile shows how a value compares to the rest of a dataset — for example a test score, height, or any other trait that is approximately normally distributed. Enter your own value along with the mean and standard deviation of the reference group, and this calculator instantly works out your z-score and matching percentile.
Fraction Calculator
Adding, subtracting, multiplying or dividing fractions requires a common denominator or cross-multiplication. Enter both fractions and pick an operation for an instant, simplified answer.
Geometry Calculator
One calculator for the most-asked geometry: the circumference and area of a circle, the volume of a cylinder, the Pythagorean theorem and the area of a triangle. Choose what you need, enter your measurements and see the formula and the answer straight away — so you also learn to work it out yourself.
Maths is about patterns, ratios and logic — and with the right calculator every problem suddenly becomes clear. This category gathers free tools for percentages, fractions, powers, roots, averages and geometry, each with explanations, formulas and worked examples.
Whether you are doing homework, preparing for a test or just want to double-check something quickly: every calculator shows not only the answer but also how it was reached. That way the tool helps you learn, not just copy.
Overview
The maths category includes a percentage calculator, a fraction calculator, a geometry calculator (perimeter, area, volume and Pythagoras) and a discount calculator, among others. Together they cover the most-asked calculations from primary school to upper secondary.
How to use these calculators
- 1Pick the calculator that matches your question.
- 2Enter your own numbers; the result appears instantly.
- 3Read the formula and the step-by-step plan to understand why the answer is correct.
Common mistakes
- Ignoring the order of operations: parentheses and powers first, addition and subtraction last.
- Subtracting a percentage instead of dividing when working backwards.
- Forgetting to square for area (m² is not m).
Tips
- Round only at the end, not midway, to avoid rounding errors.
- Check your answer with an estimate: is the order of magnitude right?
よくある質問
Are these maths calculators free?
Yes, all calculators are free to use and require no account.
Do I get an explanation or only the answer?
Every tool includes the formula, a step-by-step plan and common mistakes, so you learn it yourself.
What level are they aimed at?
From primary to upper secondary school, and useful for adults refreshing their knowledge.