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The remainder when (2929)29(29^{29})^{29} is divided by 99 is

Solution

✅ Correct Option: 2

Don't get confused with the two notations:

I. (ab)c=ab×c(a^{b})^c = a^{b \times c}

II. abc=aba^{b^c} = a^b to the power cc.

The question asks for 2929×29=2984129^{29 \times 29} = 29^{841}


This can be solved through cyclicity:

PowerExpressionRemainder when ÷ 9
1

29129^1

2
2

29229^2

4
3

29329^3

8
4

29429^4

7
5

29529^5

5
6

29629^6

1

It's in the cyclicity of 5. The same remainders will repeat for powers of 6 to 10, then 11 to 15 and so forth!

Think of it like this:

Power FormRemainder when ÷ 9

296k+129^{6k+1}

2

296k+229^{6k+2}

4

296k+329^{6k+3}

8

296k+429^{6k+4}

7

296k+529^{6k+5}

5

296k29^{6k}

1

We need to express 841 in the form 6k+r6k + r:

841=840+1841 = 840 + 1 (because we know that 840840 is a multiple of 66)

Power FormRemainder when ÷ 9

296k+129^{6k+1}

2\boxed{2}

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