The reciprocal of 3 is the fraction, one third or, in decimal, 0.3 recurring. A reciprocal is essentially a fraction that is inverted or "flipped" and the fraction of 3 is 3 over 1. The reciprocal of 3 over 1 is 1 over 3, or one-third.
The reciprocal is one number that when multiplied with another number equals 1. If someone is looking to find the reciprocal of the fraction 5 over 6, or five-sixths, invert it for 6 over 5, or six-fifths. If these numbers are multiplied, the total is 1. The number 0 does not have a reciprocal.