A certain number ends with the digit
2. Moving the
2 from the end of the number to its front doubles it. Can you find this number?
(Hint: it's quite large)
This can be approached as a division problem, and thereby proceed from left to right, and it seems as easy as the multiplication approach:
1
2)2
so place a 1 to the right in the dividend:
1
2)21
2
01
requiring a zero in the quotient, and also to the right in the dividend, and brought down:
10
2)210
2
010
leading to a 5 in the quotient and dividend:
105
2)2105
2
010
10
05
leading to a 2, etc.
until eventually a 04 (not a 05) appears at the bottom that has to be divided by 2, so a 2 can be placed at the rightmost portion and zero out the bottom subtraction.

Posted by Charlie
on 20030604 04:01:16 