If the current in a circuit is distributed over several resistors we call this a parallel circuit of resistors.
There is the same voltage across all resistors.

If the total current and voltage are known, we can calculate the total
resistance according to Ohm's law from the following formula.

\(\displaystyle R_{ges}=\frac{U}{I}\)

If the values of current or voltage are unknown, we can add the conductivities of the individual resistors.

\(\displaystyle G_{ges}=G_1+G_2+G_3\) das entspricht
\(\displaystyle \frac{1}{R_{ges}}=\frac{1}{R_1}+\frac{1}{R_2}+\frac{1}{R_3}\)