Task: Question Answering
Input (English): Problem: for any positive number x , the function [ x ] denotes the greatest integer less than or equal to x . for example , [ 1 ] = 1 , [ 1.267 ] = 1 and [ 1.999 ] = 1 . if k is a positive integer such that k ^ 2 is divisible by 45 and 80 , what is the units digit of k ^ 3 / 4000 ? 
Options: a ) 0 , b ) 0 , c ) 27 , d ) 54 , e ) can not be determined
Output (English): b