If the resistance of each resistor is r, you can find equivalent resistance of parallel resistors between points A and C, D and B, C and D, as follows: R AC = R DB = (1/3)r , and R CD = (1/6)r So the above electric circuit, can be simplified as:
You must take the reciprocal of 0.67 to get the resistance of r3, r4 and r5 in parallel. Then add r6. Call the resistance that you get r100. The *reciprocal* of the resistance between A and B is: 1/r1 + 1/r2 + 1/r100. Read civil_av8r's first two lines again.