The math department decided they needed new books, and sent in an order. When they got the books back from the printers, however, they discovered that there had been a horrible mistake. Apparently the printer scrambled up all the digits in the printing press, so all the numbers reflected wrong digits. Yet somehow, these mistakes were consistent throughout the book. (For example, all instances of the digit "2" would instead use the digit "7"... but that's just an example! Don't assume that that is a clue for this puzzle!)
Some examples that were printed in the book were:
518 x 70 = 6270
6481 + 3294 = 32847
7221 x ( 3334 + 3666 ) = ?
Using this numbering system, what would this book list as the answer to the problem 7221 x ( 3334 + 3666 )?
I got 0081497 (translated into the mixed-up digits)... from 4467582. Somehow, that seems wrong, though.