LCM & GCD Calculator

LCM is the smallest number divisible by both inputs. GCD is the largest number that divides both.

What this calculator does

LCM(12, 18) = 36. GCD(12, 18) = 6.

How it works

LCM is used in adding fractions; GCD simplifies fractions.

When to use this calculator

Use this calculator whenever mental arithmetic introduces uncertainty — particularly when the result will inform a decision rather than just satisfy curiosity. Even confident mathematicians use calculation tools when precision matters.

Common mistakes

The most frequent error is rounding intermediate values before completing the full calculation. Round only the final result — rounding intermediate steps compounds errors in multi-step calculations, sometimes significantly.

Real-world scenarios

A business owner spots that revenue grew from £180,000 last year to £213,400 this year. The calculator confirms the increase is 18.6% — a figure needed for the annual report and for comparing against the industry growth rate cited in the sector report.

Frequently asked questions

What is LCM?

Least Common Multiple — the smallest positive integer divisible by both numbers.

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