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Utility Tool

Calculator

Basic calculator for quick calculations

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A straightforward calculator for everyday arithmetic, with keyboard support so you can type rather than click. It handles the four basic operations along with percentages and sign changes.

It is deliberately simple. For quick sums, a calculator that opens instantly and takes keyboard input is faster than anything with more features buried in menus.

How to use it

  1. Type numbers directly, or click the on-screen buttons.
  2. Use the keyboard for operators as well: plus, minus, asterisk for multiply, and slash for divide.
  3. Press Enter or equals to evaluate, and Escape or clear to reset.

Working out percentages

  • To find a percentage of a number, multiply and then divide by a hundred: fifteen per cent of 80 is 80 times 15 divided by 100, which is 12.
  • To add a percentage, multiply by one plus the rate. Adding twenty per cent means multiplying by 1.2.
  • To remove a percentage that has already been added, divide rather than subtract. Removing twenty per cent VAT means dividing by 1.2, not multiplying by 0.8.
  • To find a percentage change, divide the difference by the original value, then multiply by a hundred.

Frequently asked questions

Can I use my keyboard?
Yes. Number keys, the four operators, Enter for equals, and Escape to clear all work, which is considerably faster than clicking for anything more than a single sum.
How do I remove VAT or a percentage that is already included?
Divide rather than subtract. To remove twenty per cent that has been added, divide by 1.2. Subtracting twenty per cent instead gives a different and incorrect answer.
Does it follow order of operations?
The calculator evaluates as you enter, which suits sequential arithmetic. For expressions where operator precedence matters, enter the bracketed part first and use the result.