At first glance, this algorithm appears to be impractically inefficient - If formula_7contains 18 possible moves (each move, its prime, and its 180 degree rotation), that leaves formula_30(Over 1 quadrillion) cube states to be searched. Even with a heuristic-based computer algorithm like IDA*, which may narrow it down considerably, searching through that many states is likely not practical. To solve this problem, Kociemba devised a lookup table that provides an exact heuristic for formula_7. When the exact number of moves needed to reach formula_9is available, the search becomes virtually instantaneous - one need only generate 18 cube states for each of the 12 moves and choose the one with the lowest heuristic each time. This allows the second heuristic, that for formula_9, to be less precise and still allow for a solution to be computed in reasonable time on a modern computer.