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 system arrangement of the tetrahedral-octahedral honeycomb. The A root system (as well as the other rank-three root systems) may be modeled in the Zometool Construction set. In general, the A root lattice is the vertex arrangement of the "n"-dimensional simplectic honeycomb. Let "E" = R, and let Φ consist of all integer vectors in "E" of length 1 or . The total number of roots is 2"n". One choice of simple roots is: α = e – e, for 1 ≤ i ≤ n – 1 (the above choice of simple roots for A), and the shorter root α = e.