Time traveler can take 5 books with him and he has 79 books to choose from how many different ways can the books be selected

We are given:

The time-traveller has 79 books, but he can only take 5 books

since we need to find the number of ways he can choose 5 books, we know that the order in which he takes the books does NOT matter

Hence, we will use combination

Finding the number of ways:

Since we will use combination, ₇₉C₅

We know that the formula for combination is  (n!) / (r!(n-r)!)

₇₉C₅  = 79! / 5!(74!)

₇₉C₅ = 22,537,515

Therefore, the time traveller can choose 5 books in 22,537,515 different ways

well there are two answers for that.

1: you need 120 ones then that will equal up to 120.

2: you could also do one 100 and 2 tens.

those are the answers that i have thought of.