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by mental » Mon Jan 05, 2009 11:15 pm
IMO: 63492

I dont know the shorter method: but I took less than a min.

wrote down table of
7, 14, 21, 28, 35, 42, 49, 56, 63, 70

need all fours
for units to be 4, the number x unit didigit must be 2 (as 2 x 7 = 14)
we carry forward 1, now the tens digit when multiplied by 7 should give 3, that is done by 9 so we have 63+1=64
carry forward 6
we require 8 in product as 8+6=14, so we take 4
4x7=28, 28+6=34
carry forward 3
we require 1. 3X7=21
21+3=24
carry forward 2. we require 2
6x7=42, 42+2=44
both 4
we construct the number
2 + 10*9 + 100*4 + 1000*3 +10000*6 = 63492
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by mental » Mon Jan 05, 2009 11:20 pm
Alternate approach

increase 4s and check if the number is dvisible by 7

44 = no
444 = no
4444 = no
44444 = no
444444 = yes
quotient = 63492.

this method took more time than the previous one.
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by vivek.kapoor83 » Mon Jan 05, 2009 11:37 pm
mental,
i followed the same approach as your second one. Dont know where i goofed up.......it should be correct ans.but i dont know the OA.
So, if anybody can come up sol lesser than that...we hv to c.
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by mental » Mon Jan 05, 2009 11:49 pm
my first method took me less 60 sec.

though typing it was long.

The second method took more time and also there are more chances of error!!
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