How many 4 number combinations are there using numbers 1258?

4! = 4*3*2*1 = 24

Technically speaking, there are 24 permutations because that is the correct math term when the order matters. Meaning, 1258 is no the same as 1285.

In English we commonly use the Word "combination" loosely, without thinking if the order of things is important. In math we should be precise. If the order matters, we should call it a permutation. Along those lines, the locks that we commonly call combination locks would really be called permutation locks. That is why I say we use the term loosely.

So a permutation is an ordered combination.