Saturday, 15 October 2011

Puzzle-6 (CAT-2005)

The right most non zero digit of the number 302720  is 
(A)1      (B) 3     (C) 7     (D) 9          
Solution follows here:

302720 = 32720 * 102720

As 102720 produces all zeroes from right side, the last digit (unit digit) of 32720

is the right most non zero digit of 302720.

To find the unit digit of 32720:

(Please refer to “Magic of Numbers-1(unit digit...)” post of this blog)

As 2720 is multiple of 4, we consider 4th digit of the unit digit pattern of 3n.

The unit digit pattern of 3n is 3,9,7,1
Answer is (A)                

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