It’s been months since we’ve had a Mysterious Monday post, and I’ve been missing it. So here’s a mystery for you to solve.
It’s actually less of a mystery and more of a numbers puzzle. For some strange reason, it came to me at around 2am as I was trying desperately to fall asleep (stupid head cold). See what you think:
Set 1:
92-29 = 63
321-123 =198
3012 – 2103 =909
19, 901 – 10,891 = 8910
Set 2:
8765-5678 = 3087
5402 – 2045 = 3357
So what’s my point? Well, the digits in each of the sums of the first set of equations are either a 9 or they add up to 9 (e.g., 63 [6+3=9], 198 [9 and 1+8=9], 8910 [9+0=9 and 8+1=9]). BUT, although MOST such equations (where you take a number, flip it, and subtract one number from the other) result in a sum that contains 9 and/or digits that add up to 9, not ALL such flip-’em-and-subtract-’em equations do. Case in point, the second set of equations.
Any math geeks out there wanna take a stab at why this is so? I will say this: It appears that when an equation doesn’t meet the “9″ rule, it meets the “10 and/or 8 rule”. 3087=8 and 7+3. 3357 = 5+3 and 7+3.
Mysterious…
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Oh – and after some discussion, the hubs made me realize that even the answers that come out to a combination of 8 and 10, still revert back to 9 at the bottom of it all. 8+10=18, and 1+8=9. So it all comes back to 9. Nine…nine…nine…..