Two wrongs don’t make a right (except in my job application mathematics test)

I applied for a job and I was given a simple mathematics test.  Alas hardly any mathematics test is simple for me because I am what you would call in politically correct terms mathematically challenged, or in other terms a mathematical failure. I took the test and memorized what the questions were and my answers.  Later when I went home I slowly worked out the test again. I passed the test and in the question that got me through the pass mark I made two errors in working out the answer. These two errors cancelled out each other and I got the right answer!!!