How many 4 number combinations are there in numbers 1 to 6?

Answer 1

If the digits are allowed to be repeated, there are six choices for each of the four digits

in the result, so the answer is 6 x 6 x 6 x 6 = 1296.

If the digits may not be repeated, the number of choices decreases with each successive digit, so there are 6 x 5 x 4 x 3 = 360 possibilities.

The word "combination" is, strictly speaking, a choice without repetition in which the order of selection does not matter (e.g., 1234 is considered the same as 4321). Since each of the 360 permutations counted above contains every combination in 24 possible orders, there are just 360/24 = 15 possible combinations.