Question

how would I write a variable to represent the sum of four consecutive numbers if the least number is p

Answer 1

Start with what we know: Our lowest number is $p$ and we want a sum, let's call that $S$.

We know we want consecutive numbers and we want 4 of them. Numbers are consecutive if they come "one after another", that is to say: we can get from one to the other by adding or subtracting 1.

If we start with $p$ we can get consecutive numbers by repeatedly adding 1 (notice we aren't using the "or subtracting" part here because we know $p$ is our lowest number).

So: starting with $p$, adding one over and over until we've got our four numbers we have:

$p$
$p+1$
$(p+1)+1=p+2$
$(p+2)+1=p+3$

And now we can write our sum:
$S=p+(p+1)+(p+2)+(p+3)=4p+6$