Q1: Imagine you have 3 denomination of currencies (4, 6 and 11)
And you are given a target number.
Write a function that checks whether the given target is achievable via the denominations
You can use a single denomination multiple times.
I : 31
O : true
I : 9
O : false

Q2: Write a function to transform input set to output set
I : {5}
O : {5}
I : {5, 6}
O : {5, 6 , 30}
I : {5, 6, 8}
O : {5, 6, 8, 30, 40, 48, 240}