Question

Here are two questions. First questions is solved assuming repetition is not allowed but second question is solved assuming repetition is allowed. please explain this.
(No need to solve the question)

1. How many numbers of of three digits less than 500 can be found from integers 1, 2, 3, 4, 5, 6.

2. In how many ways can 4 letters be posted in 6 boxes?​

Answer 1

Answer:

120 Numbers

Step-by-step explanation:

4 possible 1st digit : 1, 2, 3, 4 (1st digits greater than 4 will be over 500)

6 possible 2nd digit : any of 1, 2, 3, 4, 5, 6, 7, except the digit we just used.

5 possible 3rd digit : any of 1, 2, 3, 4, 5, 6, 7, except the 2 digits we just used

Finally, we can form 4×6×5=120 numbers

(It was copied from Armand Le so the credit goes to him)