Steven D'Aprano added the comment: That is because of floating point rounding.
When you calculate a/23, the result is the approximate float 2.659090889061502e+18 instead of the exact integer result 2659090889061502012. Converting to an int gives you a result which is too small: py> a = 11**19 py> a - (a//23)*23 # calculate modulus with no rounding error 15 py> a - int(a/23)*23 # introduces rounding error 1395 py> a/23 2.659090889061502e+18 py> int(a/23) 2659090889061501952 py> int(a/23) - a//23 -60 By the way, are you aware of the third argument to pow()? py> pow(11, 19, 23) 15 ---------- nosy: +steven.daprano resolution: -> not a bug status: open -> closed _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue28021> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
