Question 75663
You could write this as
{{{(r+4)(r+4)(r+4)(r+4)}}} and multiply this out the long way, but there is a much faster way to tackle these sort of problems. We're going to use Binomial Expansion to expand this term. The general rule to expand {{{(a+b)^n}}} is that we start out with {{{c*a^n*b^0}}} and for each term we decrement n for a and increment the exponent for b so the 2nd terms looks like {{{c*a^(n-1)b^1}}} until we get to {{{c*a^0b^n}}} for our last term. The coefficient (c) that is placed in front of each term is found in Pascal's triangle. So for {{{(a+b)^4}}} we need to look at the row containing:

1,4,6,4,1

And these coefficients are placed in front of the variables. So if we have 
{{{(r+4)^4}}} it becomes
{{{(1)r^4*4^0+(4)r^3*4^1+(6)r^2*4^2+(4)r^1*4^3+(1)r^0*4^4}}} Notice the terms in the parenthesis are the coefficients
{{{r^4+4*4r^3+6*16r^2+4*64r+256}}}
{{{r^4+16r^3+96r^2+256r+256}}}
Hope this makes sense. If not just look at row containing 
1,2,1
This is the row of coefficients that are appended to the expansion of
{{{(a+b)^2}}}
which expands to:
{{{a^2+2ab+b^2}}}
which can be written as:
{{{(1)a^2*b^0+(2)a^1b^1+(1)a^0b^2}}}
and you can see the coefficients from the triangle in the parenthesis.