Challenges

Hint

1. Among one-digit numbers, only the numbers 2 and 5 match.

Hint

1. What sets of numbers add up to 6?
2. Given that addition is commutative, how many ways can these sets of numbers be arranged?

Hint

1. What sets of numbers have a product of 4?
2. Given that multiplication is communitative, how many ways can these numbers be arranged?

How many integers are there in the numbers 1 through 600 that are multiples of 15, and if you add the digits together they equal 6, and out fo these numbers which ones can be evenly divided by 4 and multiplied by 2, and when the digits are then added together, you get 12?

Simplify through specialization. For example, consider how many there are among the one-digit numbers (1-9), two-digit numbers (10-99), and three-digit numbers (100-999).

For every 10 numbers there is one eight.