Q77·CSAT · Prelims 2025
Remainder of 9^3+9^4+...+9^100 mod 6
NumericalRemainders & CyclicityNumber theory● Hard
Question
What is the remainder when 2^1 9^3 + 9^4 + 9^5 + 9^6 + ... + 9^{100} is divided by 6?
Options
aAnswer
0
b
1
c
2
d
3
Explanation
Every 9^k mod 6 = 3, there are 98 terms, 98 × 3 = 294, 294 mod 6 = 0 Answer: (a).
Question details
Year
2025
Paper
CSAT
Question
Q77
Section
Numerical Ability
Sub-topic
Remainders & Cyclicity
Type
Number theory
Difficulty
Hard
Source hint
Number theory
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