Every number is a little building. And like any building, it's made of smaller blocks stacked together in a particular way. The question is: how do we pull a number apart to see exactly which blocks it's made of?

First, a definition you can carry the whole way. A factor is a number that divides evenly into another number, with nothing left over. Ask of 12: "Does 3 fit into you cleanly?" Yes — 3 × 4 = 12. So 3 and 4 are both factors of 12. No crumbs, no remainder.

One way to find factors is brute, cheerful checking. Walk up from 1 and knock on each door: "Do you divide me evenly?" For 12, the numbers that say yes are 1, 2, 3, 4, 6, and 12. Those are all of 12's factors — the complete crew that can build it through multiplication.

But some numbers are stubborn loners. Try 7. Knock on every door and only two open: 1 and 7 itself. Numbers like this — divisible only by 1 and themselves — are called prime numbers. They're the unbreakable blocks. You can't split a prime into smaller whole pieces.

This is the big idea. Every number that isn't prime can be broken down into primes — and only primes. Primes are the true LEGO bricks of arithmetic. Once you reach them, you can't break further. Finding those special bricks for a number is called prime factorization.

Here's the trick for doing it. Take your number and split off any prime you can — start small, with 2, then 3, then 5. Take 60. It's even, so pull out a 2: that leaves 30. Still even, pull out another 2: that leaves 15. No more 2s fit, so move up.

Keep climbing. Does 3 divide 15? Yes — 15 becomes 5. And 5 is prime, so we stop. Lay out everything we pulled off: 2, 2, 3, and 5. Multiply them back and they rebuild 60 perfectly. Those four primes are the secret recipe of 60.

And here's the magic part, the rule mathematicians lean on. Every number has exactly ONE prime recipe — no other set of primes can build it. 60 is always 2 × 2 × 3 × 5, no matter how you start splitting. The order you pick the primes never changes the final bricks.