IB Mathematics SL Prep

Key Takeaway: If you memorize the sequence 1-4-2-8-5-7 you can calculate any number divided by 7 quickly.

1/7 = .142857
2/7 = .285714
3/7 = .428571
4/7 = .571428
5/7 = .714285
6/7 = .857142

Editor’s Note: In one of my case interviews, I was asked to calculate how many $70 devices I would need to reach $2 million in revenue. Since someone had taught me this trick, I dispensed with estimating, and told the interview the answer was 28,571.428571. I got the job.