Explain why the result is always the original number followed by your age

It isn't.  For example, if I integrate the function [ 2sin(θ) + 3cos(θ) ] between
the limits of -π and +π, my age does not appear anywhere in the result.

It depends on how the calculation is set up, and what steps you go through
to get the result.  You haven't told us anything about that.