Every whole number is built from primes the way every word is built from letters — 60 is 2 × 2 × 3 × 5, and no other combination of primes multiplies to 60. Finding those building blocks is prime factorization, and the workhorse method is the factor tree: split the number into any two factors, split those, and keep going until only primes remain. For 84, you might split into 12 × 7, then 12 into 4 × 3, then 4 into 2 × 2, leaving 2 × 2 × 3 × 7 — the leaves of the tree are the answer, and every path down gives the same leaves.

The payoff is practical: prime factors reveal the greatest common divisor (take the shared primes) and the least common multiple (take all primes at their highest powers), simplify fractions to lowest terms, and underpin RSA encryption securing your credit card. A quick divisibility toolkit speeds the hunt: even numbers hide a 2, digit-sums divisible by 3 hide a 3, numbers ending in 5 hide a 5. This calculator multiplies out a candidate factorization to verify it: type the product of all but one of your prime factors in the Variable A box and the last factor in the Variable B box — for 60 = 2 × 2 × 3 × 5, enter 12 and 5. The Result box shows 60, confirming the factors rebuild the original number.

With the pre-filled defaults — Variable A 10, Variable B 5 — the Prime Factor Calculator returns Result 50.0000. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.