Combinations Question

Question

How many combinations are there of the letters A, B, C, D, if I take 3 at a time? Please Explain.

Combinations: Permutations:

A B C ABC ACB BAC BCA CAB CBA

A B D ABD ADB BAD BDA DAB DBA

A C D ACD ADC CAD CDA DAC DCA

B C D BCD BDC CDB CBD DBC DCB

Answer 1

Combinations: order does not make a difference. ABC is the same as CBA

Permutations: order does make a difference, ABC is different from CBA.