How many distinguishable ways are there to write 9 as the sum of 1's, 2's, 4's, and 5's, where the order of the addends matters? For example, 4 + 4 + 1 and 1 + 4 + 4 are two different ways.
From your example, you can obviously repeat the digits, but to what extent?
Can you have: 1+1+1+1+1+1+1+1+1==9, or: 2+2+2+2+1==9......and so on.
You have to clarify the question.
