I still remember the "minimal effort" definition,

so "using **only** pen and paper" should not preclude using one's head as well.

I did not post my solution, since it looked d1 to me. Only after reading previous posts. I have decided to explain how it was addressed by me, and although to check my GUESS i used one line of excell, I've branded it a **p&p d1** problem.

Clearly n is a 3-digit number, slightly over 133 (quick mental process of looking at the equation).

The last digit of **5TH POWER OF ANY NUMBER** IS ALWAYS

the SAME AS The last digit of **THAT NUMBER.**

**3+0+4+7= 4 mod 10**

**my 1st guess was 154,**

lowered it to 144 and checked it (just to make it sure).

felt sorry , that it was not my 1st guess, but..what the heck...

**p.s. The checking was excel-aided, could do it p&p way.**