Decisions

Summary:

We can multiply together the number of choices in each decision, if the decisions are independent.

1. Find the number of ways that digits 1 through 6 can be used to form a 4 digit number. Each digit can be used up to 4 times.

2. The prime factorization of $720$ is $2^4\times 3^2\times 5$. How many factors does $720$ have?

Hint 1

Each factor of 720 has of its own up to four factors of 2, two factors of 3, and one factor of 5.

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