63 - the highest value unsigned number which may be held in 6 bits (111111 in binary and 77 in octal) and represents the value -1 in a six bit twos complement number system. As a sign and magnitude representation it represents the value -31. We'd best not go into the range of values represented by all the possible floating point representations eh?

64 is both a square (8 squared) and a cube (4 cubed). It is represented in octal by 100 and in binary by 1,000,000. 64 is also the smallest number having six prime factors.

Shame this thread seems to have stalled - is everyone avoiding 69 for some reason? I myself am doing a body swerve on the obvious reference and choose rather to edify readers with the fascinating fact that the square and the cube of 69 together use each and of the digits 0 - 9 once and once only! (69² =4,761 and 69³ = 328,509). Just think - had you not signed up to the Windows 7 Forums and not seen this thread you could have gone through your entire life in blissful ignorance of this essential fodder for the grey matter