|Posted: August 18, 2006, 1:01 am - IP Logged|
I'm not sure if they taught it in your grammar school, but when we were learning multiplication in 3rd or 4th grade, I remember learning "casting out nines" which stuck with me all my life. You can use many combinations in your 7 digits to do it, but of course you'll always get 9. So 3+6 in the middle and 11+7 and 2+7 all add up to 9. 9+9+9 = 27 or 2+7 which is 9 which is a very mystical number.
Good luck, Pac!