How to use the Simple Calculator
- Tap the digits and operator you need.
- Use % for remainder-style modulo work, or type a decimal for straight percentages.
- Press = for the answer.
- Press C to start again from zero.
How the calculation works
A simple calculator trades features for speed of entry. There are fewer keys to hunt for, larger targets on a phone, and no mode state to get stuck in — a common frustration with scientific models, where a stray DEG/RAD setting silently changes every trigonometric answer.
The percent key here performs modulo (the remainder after division), which is what most quick checks want: 17 % 5 returns 2. For percentage-of-a-value work, multiply by the decimal instead — 15% of 240 is 240 * 0.15. Keeping these two ideas separate avoids the ambiguity built into old pocket calculators, where the % key behaved differently depending on which operator preceded it.
a % b = a − b × floor(a ÷ b) ; p percent of v = v × (p ÷ 100)Source: IEEE 754 double-precision arithmetic; standard definition of the modulo operation.
Worked example
Working out how many full boxes of 12 you can fill from 100 items, and what is left over.
- Enter 100 / 12 → 8.333, so eight full boxes.
- Enter 100 % 12 → 4 items left over.
Eight full boxes with four items remaining.
Frequently asked questions
How is this different from the basic calculator?+
Fewer keys and a percent/modulo key in place of bracket entry. The maths engine is identical.
Does the percent key work like a shop discount?+
No — it returns a remainder. For a discount, use the percent off calculator or multiply by the decimal.
Can I use my keyboard?+
Yes, the display accepts typed input including operators.
Is there a memory function?+
Not in this layout. Keep the running expression on screen instead — it is visible and editable, which is safer than a hidden memory register.
Last reviewed September 1, 2026. We review this page whenever the underlying formula, tax year, published rate or standard changes.