Question

How many 5-digit numbers can be formed using the digits 1, 2, 3, 4, 5, 6, 7 if repetition of digits is not allowed?

Answer 1

Answer:

2520

Step-by-step explanation:

7×6×5×4×3 = 2520

Imagine □□□□□

For the 1st □, there are 7 choices

For the 2nd □, there are 6 choices (since 1 out of the 7 numbers is already used)

For the 3rd □, there are 5 choices (since 2 out of the 7 numbers are used)

And so on...