How to use: For example, for Ohm's law, V = IR, where V = voltage, I = current, and R = resistance, if voltage is the unknown value, then type voltage in the Answer/Type cell. Type the numerical value of the current in the 1/Value cell type the word current in the 1/Type cell, type the numerical value of the resistance in the 2/Value cell, type the word resistance in the 2/Type cell, and press enter or click on calculate to get the value of voltage.