Question

A locked door is opened by turning the knobs
shown below to a particular combination of
numbers.
How many possible number combinations are
there for opening the locked door?

There is a picture of 3 knobs, each with four numbers being: 1, 2, 3, and 4. Maybe you could also explain a little?
A) 4
B) 12
C) 24***
D) 64

Answer 1

there are 4 choices for each knob. Since each knob is independent of the others, that gives
4*4*4=64
choices.

24 would be correct if no duplicate digits were allowed.

Answer 2

Oh ok, thank you so much