Aiding winding sources are checked against an output-voltage ceiling. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Aiding-polarity row 1
First source stays 6 V. Aiding second source 2 V gives output 8 V against a 10 V ceiling, so margin is 2 V.
m=2Vpass
Aiding-polarity row 2
First source stays 6 V. Aiding second source 4 V gives output 10 V against a 10 V ceiling, so margin is 0 V.
m=0Vpass
Aiding-polarity row 3
First source stays 6 V. Aiding second source 6 V gives output 12 V against a 10 V ceiling, so margin is negative 2 V.