There's always a time/space tradeoff involved, see for example the Wallace tree multiplier [1], which is indeed O(log n) in time. [1] https://en.wikipedia.org/

There's always a time/space tradeoff involved, see for example the Wallace tree multiplier [1], which is indeed O(log n) in time. [1] https://en.wikipedia.org/wiki/Wallace_tree https://en.wikipedia.org/wiki/Wallace_tree