What is the latgest number you can make with 3,5, and 7

105 if you multiply all three numbers together

If we cannot make operations with them, then the biggest number is that we create using the biggest number at the left side of the number, and descending in order to the right:

753

that would be the biggest number.

But what if we can make operations with those numbers?

we could multiply them:

7*5*3

order do not matter for multiplication, and there are other operations as well, as high powers for numbers.