help!

find the remainder when 3100 is divided by 100

(post ur entire method please )

25 Answers

11
Subash ·

no i dunno the answer i only know that it is not 1

but method please that would help me a lot

1
KR ·

http://targetiit.com/iit_jee_forum/posts/finding_last_two_digits_3747.html

1
KR ·

if the power had a 2 digit prime factor we can find last 2 digits easily .....but the other one is tough.......

1
MATRIX ·

hey ankit wats the problem with prime number......hey yaar........solve 3100 u'll get the answer....

1
ankit mahapatra ·

but p is 100 and it is not prime number.

1
MATRIX ·

hey KR ithevidunaaa ee type theorems konduuvarunaduuu.....

1
KR ·

easy way::

Fermat's little theorem states that if p is a prime number, then for any integer a, ap − a will be evenly divisible by p..
ap≡a(mod p)

A variant of this theorem is stated in the following form: if p is a prime and a is an integer coprime to p(eg 4 is coprime to 3), then ap − 1 − 1 will be evenly divisible by p.
ap-1≡1(mod p)

1
The Scorpion ·

3100 = (80+1)25 = 25C0.8025 + 25C1.8024 + ... + 25C24.80 + 1

=> last two digits of 3100 are 0,1 respectively...

so when 3100 is divided by 100, the remainder will be 1... hence statement I is true...

d last digit of 3100 is 1... hence statement 2 is also true...

but statement II partly explains statement I ... even though d last digit of d expansion is 1, for d remainder to b 1 when divided by 100, the last but one digit (or d digit in ten's place should b 0)... hence d given statement is necessary but not sufficient condition to declare statement I...

well, the answer must b A... :)

1
KR ·

@SUBASH check ur ans i'm getting last 2 dits 01

1
MATRIX ·

3100=(32)50

(32)50=950

(92)25=8125

=(81)24.81

81 raised to any no /100 remainder is 1........because as we go simplifying we will get a 1 at the first place..........Remainder is always 1..........

1
MATRIX ·

hey subash..[1][1][1].......

33
Abhishek Priyam ·

Deleted that...

[5]

actually did write 3.(33)33

33=9 [5] and then edited it... so that become wrong...(33 was odd naa so just changed 33 to 50 everywhere.. ) :P
:P

21
tapanmast Vora ·

priy : ye kaise ???

(10-1)^50 = 9^50
=-(1-10)^50 = -(-9)^50 [5] [11]

11
Subash ·

actually the question asked was different

Statement 1: when 3100 is divided by 100 remainder is 1

Statement 2: The unit digit in 3100 is 1

11
Subash ·

@KS ur answer is wrong

answer to that assertion question is D ie stat1 false stat2 true

11
Subash ·

@tapanmast thanks for the effort but i would like to see an application rather than the link :)

1
krish1092 ·

3^100=9^50=(10-1)^50
Expand it,
50C010^50-......-500+1
=100(m)+1
Hence unit digit is one
So,When 3^100 is divided by 100,remainder is 1

21
tapanmast Vora ·

http://mathworld.wolfram.com/Congruence.html

http://en.wikipedia.org/wiki/Modular_arithmetic

11
Subash ·

not a problem :)

1
KR ·

takes time but will post

11
Subash ·

yup i dunno congruences :(

so please post

1
KR ·

congruences ....modulo

should I post it???

11
Subash ·

can you elaborate it a bit KR! im not getting it yet:(

1
KR ·

this like finding last 2 digits

1
vector ·

sry did nt read the q carefully

Your Answer

Close [X]