# Calculators

- Human page: https://happytails.ai/en/calculators/
- Markdown: https://happytails.ai/en/calculators.md
- Structured JSON: https://happytails.ai/agents/en/calculators/index.json
- Visibility: public

## Page guide

Find the tool you need, then open it to get started.

## All calculators

- [Average](https://happytails.ai/en/calculators/average/): Find the mean, median, sum, minimum, and maximum of a list of numbers. ([Markdown](https://happytails.ai/en/calculators/average.md))

- [Break even](https://happytails.ai/en/calculators/break-even/): Find how many units cover your fixed and variable costs. ([Markdown](https://happytails.ai/en/calculators/break-even.md))

- [Circle](https://happytails.ai/en/calculators/circle/): Calculate a circle’s diameter, circumference, and area from its radius. ([Markdown](https://happytails.ai/en/calculators/circle.md))

- [Coin flip](https://happytails.ai/en/calculators/coin-flip/): Flip a virtual coin and get Heads or Tails. ([Markdown](https://happytails.ai/en/calculators/coin-flip.md))

- [Dice roller](https://happytails.ai/en/calculators/dice-roller/): Roll virtual dice and see each roll and the total. ([Markdown](https://happytails.ai/en/calculators/dice-roller.md))

- [Discount](https://happytails.ai/en/calculators/discount/): Calculate the saving and final price after a discount. ([Markdown](https://happytails.ai/en/calculators/discount.md))

- [Fractions](https://happytails.ai/en/calculators/fractions/): Add, subtract, multiply, or divide two fractions. ([Markdown](https://happytails.ai/en/calculators/fractions.md))

- [Lcm](https://happytails.ai/en/calculators/lcm/): Find the least common multiple of whole numbers. ([Markdown](https://happytails.ai/en/calculators/lcm.md))

- [Margin](https://happytails.ai/en/calculators/margin/): Calculate profit and profit margin from cost and selling price. ([Markdown](https://happytails.ai/en/calculators/margin.md))

- [Markup](https://happytails.ai/en/calculators/markup/): Calculate profit and markup from cost and selling price. ([Markdown](https://happytails.ai/en/calculators/markup.md))

- [Percentage](https://happytails.ai/en/calculators/percentage/): Find a percentage of a number. ([Markdown](https://happytails.ai/en/calculators/percentage.md))

- [Percentage change](https://happytails.ai/en/calculators/percentage-change/): Calculate the percentage increase or decrease between two values. ([Markdown](https://happytails.ai/en/calculators/percentage-change.md))

- [Random number](https://happytails.ai/en/calculators/random-number/): Generate random whole numbers within an inclusive range. ([Markdown](https://happytails.ai/en/calculators/random-number.md))

- [Ratio](https://happytails.ai/en/calculators/ratio/): Simplify a ratio of two whole numbers. ([Markdown](https://happytails.ai/en/calculators/ratio.md))

- [Rounding](https://happytails.ai/en/calculators/rounding/): Round a number to a chosen number of decimal places. ([Markdown](https://happytails.ai/en/calculators/rounding.md))

- [Scientific notation](https://happytails.ai/en/calculators/scientific-notation/): Write a number in scientific notation. ([Markdown](https://happytails.ai/en/calculators/scientific-notation.md))

- [Square footage](https://happytails.ai/en/calculators/square-footage/): Calculate rectangular floor area in square feet and square meters. ([Markdown](https://happytails.ai/en/calculators/square-footage.md))

- [Standard deviation](https://happytails.ai/en/calculators/standard-deviation/): Calculate the mean and standard deviation of a set of numbers. ([Markdown](https://happytails.ai/en/calculators/standard-deviation.md))

- [Tip](https://happytails.ai/en/calculators/tip/): Calculate a tip, the total bill, and each person’s share. ([Markdown](https://happytails.ai/en/calculators/tip.md))

- [Triangle](https://happytails.ai/en/calculators/triangle/): Calculate a triangle’s perimeter and area from its three side lengths. ([Markdown](https://happytails.ai/en/calculators/triangle.md))

- [Volume calculator](https://happytails.ai/en/calculators/volume-calculator/): Calculate the volume of a box, cylinder, or sphere. ([Markdown](https://happytails.ai/en/calculators/volume-calculator.md))

## Start with the right quantities and assumptions

An everyday calculator is most useful when it explains its inputs, units and formula. Percentage changes, discounts and ratios describe different relationships even when they involve the same numbers.

## How to choose your next step

Label the original value and the quantity being compared. Check whether a rate is entered as a percentage or a decimal, and round at the appropriate stage.

## Common questions about calculators

### Why do two percentage calculations give different results?

The denominator matters. Increasing a value by a percentage and then decreasing the new value by the same percentage will not generally return the original amount.

### Should intermediate values be rounded?

Rounding at every step can accumulate error. Keep enough precision during a calculation and round the final result according to the task.