When a single electrochemical reaction occurs at an electrode (i.e. all other electrochemical reactions may be neglected): \[I=I_{\text{a}}+I_{\text{c}}\] where I is the total current, Ia is the positive partial anodic current and Ic is the negative partial cathodic current. When more than one reaction is significant the reactions may be numbered and the numbers used as subscripts: I1,a, I1,c, I2,a, etc. Then: \[I=\sum I_{i,\text{a}}+\sum I_{i,\text{c}}\]