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Find the last three digits of 2988^678?
Read Solution (Total 8)
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- Answer is:184
((12*12)^4)^169*(12)^2;
((144)^4)^169*(144);
(6*6)^169*(144);
36*144;
184;is ans; - 11 years agoHelpfull: Yes(6) No(7)
- 144 is the answer
- 11 years agoHelpfull: Yes(4) No(4)
- http://www.youtube.com/watch?v=_ip94NlNwHo
learn from this video because i will not be able to explain you because its complicated. - 11 years agoHelpfull: Yes(3) No(2)
- 504 iz d ans
- 11 years agoHelpfull: Yes(1) No(0)
- This is a tough question.
Last three digits of an expression is nothing but the remainder when we divide the given expression by 1000.
So 29886781000=(−12)6781000=126781000
We write 1000 as 8 ×125. So we separately find the remainders by dividing the given number by 8 and 125.
Given expression is clearly divisible by 8. Also
Euler totient theorem says [aϕ(N)N]Remainder=1
Here ϕ(N) is the number of co primes of a number N. In this case ϕ(125) = 100.
So (12100)6.1278125=16.1278125
Now 1278=478.378=(1+15)39.(10−1)39
(1+15)39.(−1)39(1−10)39
- (1+39C1.15+39C2.152.... ). (1+39C1.10+39C2.102−39C3.103....
If you observe clearly, 153 and 103 are 15 multiples. So we can omit the remaining terms.
-(1+39.15 + 39.19.152 ).(1-39.10 + 39.19.102)
By writing 39 as 40-1 we can simplify this equation fast.
-(1+(40-1).15 + (40-1).19.152).(1-390 + (40-1).19.100
-(1+100 - 15 - 19.152 ).(1-140 - 19.100)
-(101 - 15 - (20-1).152).(1-140+100)
-(101-15+100).(-39)
-(61).39
-2379 = 4
So the remainder is 4.
The original expression is in the format of N = 8K = 125 L + 4
The minimum number satisfies this condition is L = 4.
So 125 (4) + 4 = 504
So answer is 504 - 9 years agoHelpfull: Yes(1) No(0)
- @Rohit.. How ((144)^4)^169=(6*6)^169?? Can yu please explain??
- 11 years agoHelpfull: Yes(0) No(5)
- answer is 2
- 11 years agoHelpfull: Yes(0) No(11)
- 184;is ans;
- 11 years agoHelpfull: Yes(0) No(0)
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