2 ms·
Had a classmate who was a prodigy. He did the same cubic roots trick, except he could work with non-integers. e.g. By your method, if I ask for the cube root
by rprospero 12y ago
Had a classmate who was a prodigy. He did the same cubic roots trick, except he could work with non-integers.
e.g. By your method, if I ask for the cube root 270119, you'd say 69, but the answer is is closer to 64.64. He could usually give the right answer to within four sig digs.
The way I understood his explanation, he'd do all the calculations in log space, so he could pull out high order roots, but the answers were less accurate.
- TheLoneWolfling 12y agoHmm... Convert to binary, take (approximate) log2 of the number, divide by three, take 2 to the power of ans? (Binary both because most programmers know powers of two, and because you are more accurate when you know the closest power of two to something than the closest power of 10) Even just approximating log2(270119) as 18 gives you an answer of 64.