The unit digit in $${\left( {122} \right)^{173}}$$ is ?
Options:
A . 2
B . 4
C . 6
D . 8
Answer: Option A In this case: 122 (powers of the last digit 2 ) 21 = 2 22 = 4 23 = 8 24 = 16 25 = 32 26 = 64 27 = 128 28 = 256 29 = 512 …… As you can see, the pattern repeats every 4th power (2, 4, 8, 6). We have to find 122173 Hence, remainder when 173 is divided by 4 = 1 (which corresponds to the 1st number of the pattern) Thus, unit digit of 122173 = 2
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