Password - non-static

When a typical iPhone user enters their PIN in public, the chance for a creep to peep occurs.

If the PIN, instead of being static, the same PIN every single time, were a user-designated dynamic, could greater security be achieved?

If a system using the following:

1. sum of integers, e.g., a code (PIN) of 11, could be entered by the digits 7 and 4, or 3 and 4 and 4, or 2 and 2 and 7, etc.

2. product of integers, e.g., code (PIN) of 24 could be achieved by 6 and 4, or 2 and 2 and 6 or 2 and 2 and 2 and 3, etc.

That's all I have.

Alan