Articles

Floor, ceiling, round and mod each handle a number differently. See exact worked examples, a comparison table, and how each one works on a calculator.

Learn how the power, square root, cube root and reciprocal keys work on a calculator, with exact worked examples for each operation.

The negative sign and the subtraction key look similar but do different jobs. Learn the difference, the worked examples, and the error it causes when confused.

Learn exactly what factorial, nPr and nCr mean, with the real formulas and worked examples: 5! = 120, 5P2 = 20, 5C2 = 10.

Learn exactly what the Ans button does, how to chain calculations without retyping numbers, and how calculator history differs from Ans, with worked examples.

DEG, RAD and GRAD are the three angle units a calculator can use. Learn what each one means, the exact conversion formulas, and worked examples for all three.

Two calculators can show two different answers for the same problem. Follow a five-step checklist to verify any online calculator’s result by hand.

Parentheses force part of a calculation to happen first. See exact worked examples with and without them, plus nested parentheses and common mistakes.

EXP is not the power key. Learn what EXP really does, how it enters scientific notation fast, and why mixing it up with x^y causes wrong answers.

Log, ln and log2 look alike but use different bases. See exact definitions, worked examples, and how to convert between them on a calculator.