Question

A suitcase has a lock on it consisting of three numbers. Each number could be any

number 0-9. The only restriction is that two numbers in a row cannot be the same
(e.g. you couldn’t use 322 because the 2’s are adjacent but you could use 343
since none of the same numbers are adjacent).






A. 1,000

B. 5040

C. 7290

D. 810

Answer 1

Answer: 810

Explanation:

There are 10 numbers to choose from. Since the 2nd digit and 3rd digit cannot repeat the number before it, they only have 9 numbers to choose from.

1st digit and 2nd digit and 3rd digit

10 choices x 9 choices x 9 choices = 810