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Another last digit (Posted on 2004-09-07) Difficulty: 1 of 5
What's the last digit of 11^2003 times 7^2004 times 13^2005 ?

See The Solution Submitted by Federico Kereki    
Rating: 2.5000 (4 votes)

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Solution Alternative Methodology Comment 10 of 10 |
(In reply to Puzzle Solution by K Sengupta)

At the outset, we have:

11^2003 times 7^2004 times 13^2005
= (11*7*13)^2003 times 7 times 13^2
= (1001)^2003 times (7*13) times 13
= (1001)^2003 times 91 times 13

Now,we observe that:

The last digit of 1001^2003 is 1
The last digit of 91 is 1
The last digit of 13 is 3

Consequently, the required last digit of the given expression
= 1*1*3
= 3


  Posted by K Sengupta on 2008-04-25 07:09:20
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