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Divisibility by 7 (Posted on 2005-05-22) Difficulty: 2 of 5
(2222^5555 + 5555^2222) is or isn't divisible by 7 ?

Just pencil and paper.

See The Solution Submitted by pcbouhid    
Rating: 2.0000 (3 votes)

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re: Divisible by 7 | Comment 2 of 8 |
(In reply to Divisible by 7 by Ravi Raja)

Agreed.

2222%7=3
2222*3%7=2
2222*2%7=6
2222*6%7=4
2222*4%7=5
2222*5%7=1
2222*1%7=3

So our series is 326451. Now 5555%6=5. So the fifth number is 5.

5555%7=4
5555*4%7=2
5555*2%7=1
5555*1%7=4

So our series is 421. Now 2222%3=2. The second number is 2.

5+2=7. 7%7=0, so 2222^5555+5555^2222 is divisible by 7.


  Posted by Justin on 2005-05-22 17:02:50
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