How do you calculate the total resistance of two resistors, R1 and R2, when they are in series and when they are in parallel?

When resistors are in series you may add up their resistances to find the total resistance, R_Total= R1 + R2. However, when resistors are in parallel, it gets a little more complicated. You must use the equation R_Total=1/((1/R1)+(1/R2)).