Two distinct numbers are selected simultaneously and at random from the set (1, 2, 3, 4, 5, 6, 7). What is the probability that the smaller one divides the larger one? Express your answer as a common fraction.
7 C 2 = 21 choices for the two numbers
1 2 3 4 5 6 7
2 4 6
3 6 are the combos that 'divide' 9 out of 21 = 3/ 7