Question

Suppose you are to create a three-digit number from the set of numbers {1,2,3,4,5,6,7}. How many possible three-digit numbers can you create if you are allowed to use a number only once.

Answer 1

Set of numbers = {1, 2, 3, 4, 5, 6}

We have to create 3 digit number from the above set of numbers.

Repetition of number is not allowed.

We can use 6 numbers for first digit, 5 numbers for second digit and 4 numbers for third digit.

Number of possibilities = 6 * 5 * 4 = 120