13th root 13th root Extracting the 13th root of a number is a famous category for the mental calculation world records. The challenge consists of being given a large number (possibly over 100 digits) and asked to return the number that, when taken to the 13th power, equals the given number. For example, the 13th root of 8,192 is 2 and the 13th root of 96,889,010,407 is 7. Extracting the 13th root has certain properties. One is that the 13th root of a number is much smaller: a 13th root will have approximately 1/13th the number of digits. Thus, the 13th root
Root of unity modulo n it is not a primitive root, then there would be some divisor ℓ of "k", with formula_57. In order to exclude this possibility, one has only to check for a few ℓ's equal "k" divided by a prime. That is, what needs to be checked is: Among the primitive "k"-th roots of unity, the primitive formula_23-th roots are most frequent. It is thus recommended to try some integers for being a primitive formula_23-th root, what will succeed quickly. For a primitive formula_23-th root "x", the number formula_30 is a primitive formula_25-th root of unity. If "k" does not divide formula_23,