Common divisors and common multiples, both at once

For two integers, the GCD is the largest number dividing both and the LCM the smallest number both divide into. For 48 and 18 the GCD is 6 and the LCM is 144. The GCD comes from Euclid's algorithm (repeated remainders) and the LCM derives from it via |a × b| ÷ GCD — the page shows the product check so the pair visibly agrees.

Enter any two integers (they round to whole numbers first). Dividing numerator and denominator by the GCD reduces a fraction to lowest terms; the LCM gives the common denominator for adding fractions and the meeting point of two repeating cycles — bus schedules, shift rotations, and tile grids that must align without cutting.

It handles pairs only, works on rounded integers rather than decimals, and does not factor further — for full prime breakdowns, use the prime-factor tool.

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