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Mental Arithmetic (Posted on 2003-10-05) Difficulty: 3 of 5
I can multiply any three-digit number by 1667 in my head, usually in less than 10 seconds.

Also, to make it even more impressive, I come up with the digits of the result in proper order (not in reverse!)

How can I do this?

See The Solution Submitted by nellie    
Rating: 3.3333 (6 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
re: none | Comment 15 of 21 |
(In reply to none by Lee)

well, lee, maybe there is another way that the poster is seeking. but for me,
division by 6 is easy if i focus on the 7-digit number in my mind's
eye...'cos from that point onward, i only think of two digits at a time
(as you illustrated) and i am able to rattle off the answer. is it
possible to make a mistake once in a while? sure...but i can't think
of another way of coming up with the answer from left to right
without a long division being involved somewhere. i guess we'll
find out soon enough, though. :-)
-mohan.

Edited on October 14, 2003, 3:38 am
Edited on October 14, 2003, 3:52 am
  Posted by mohan on 2003-10-14 03:25:01

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