CUET UG Mathematics Applied Logarithms and Indices Previous Year Question Paper and Solution with PDF

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Qus : 1 CUET UG Mathematics Applied PYQ

The number at unit place of number $17^{123}$ is:

1
2
3
4
Go to Discussion

Unit digit depends on $7^{123}$

Cycle of unit digits of powers of 7:

$7^1=7$

$7^2=49$ → 9

$7^3=343$ → 3

$7^4=2401$ → 1

Cycle repeats every 4.

Now,

$123 \mod 4$

$123=4\times 30+3$

Remainder = 3

So unit digit same as $7^3$

Unit digit = 3

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