The answer is 8C6 = 8!/[6!*(8-6)!] where n! = 1*2*3*...*n
So, the answer is 28.
There are 6 groups.
If the six numbers are all different, then the answer is 6C4 = 6*5/(2*1) = 15
2 groups
5
If the order of the 4 numbers matters, then there are (6 x 5 x 4 x 3) = 360 .If the order of the 4 numbers doesn't matter, then there are 15 different groups of 4.
I doubt it. You can get 7,676,760 different groups of 6 numbers out of a bucket of 40 numbers. No website is going to give you that much output for a single input.
Any "cube" has 6 faces, so you could have 6 different numbers, as on dice.
Number of combinations = 45C6 = 45!/6!(45-6)! = 8,145,060
6, as long as they are all different
30
6 if order doesn't matter
There are about four different groups of crystals structures that are available in the minerals. The four have different orientations of the close-packed layers.