How to combine resistors in parallel to achieve the desired total resistance?

To combine resistors in parallel to achieve the desired total resistance, you need to use the formula 1/Rtotal 1/R1 1/R2 1/R3 ... 1/Rn, where Rtotal is the total resistance and R1, R2, R3, etc. are the resistances of the individual resistors. Calculate the total resistance by adding the reciprocals of the individual resistances and then taking the reciprocal of the sum.