To calculate the voltage at a specific resistor in a parallel circuit, apply Kirchhoff's rules to determine the current through that resistor. Use Ohm's law to find the voltage once the current is known. A specific example discussed involved calculating the current through a 10-ohm resistor with and without a 25-ohm resistor shorted out, yielding results of 7.14 amps and 6.9 amps, respectively. Participants encouraged sharing calculations for verification. The conversation concluded with the original poster successfully resolving their question.