Numbers Calculators
8 free numbers calculators — all with step-by-step working shown
Primes, factors, HCF, LCM, square roots and rounding — all with working.
Prime Number Checker
Check if any number is prime — with explanation
Prime Factorisation Calculator
Break any number into its prime factors with a factor tree
HCF Calculator
Find the highest common factor using the Euclidean algorithm
LCM Calculator
Find the lowest common multiple with step-by-step working
Factors Calculator
Find all factors of any number instantly
Square Root Calculator
Find the square root of any number with working shown
Cube Root Calculator
Find the cube root of any number with working shown
Rounding Calculator
Round to decimal places or significant figures with working
Why step-by-step working matters
Number theory tools covering the full range of GCSE maths. Check if a number is prime, find prime factorisation, calculate HCF and LCM using the Euclidean algorithm, find all factors of a number, and round to any number of decimal places or significant figures — with complete working shown.
Unlike calculators that show only the final answer, every Pythagorist tool displays the complete method — the same working you would write in an exam. This means you can understand the process, not just copy a number. Students who understand the method score more marks, because examiners award points for correct working even when the final answer contains an arithmetic error.