ObraPlus

Here is a precalculus question on function domain. Be careful!

Happy new school year!
Here is a fun algebra problem to start.

For an integer N, P(N) and S(N) are defined as a product and sum of the digits of N respectively. If N = P(N)+S(N), what is the unit digit of N?

Join us for the 2025–26 school year! Our new hands-on class, Physics in Experiments, introduces students to the exciting world of physics through engaging activities. Classes begin soon —don’t miss out!