Find the last 2 digit of 31^26
Question
Find the last 2 digit of 31^26
Solution
To find the last two digits of 31^26, we can use the concept of cyclicity.
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First, we need to find the cycle of the last two digits of powers of 31.
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The last two digits of 31^1 is 31, 31^2 is 961 (so 61), 31^3 is 29791 (so 91), 31^4 is 923521 (so 21), 31^5 is 28629151 (so 51), 31^6 is 887503681 (so 81), 31^7 is 27512614111 (so 11), 31^8 is 852891037441 (so 41), 31^9 is 26439622160671 (so 71), 31^10 is 819628286980801 (so 01), and 31^11 is 25397369317840631 (so 31).
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We can see that the cycle repeats every 10 powers (31, 61, 91, 21, 51, 81, 11, 41, 71, 01, 31).
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Now, we need to find the remainder when 26 is divided by 10, which is 6.
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So, the last two digits of 31^26 will be the same as the last two digits of 31^6, which is 81.
So, the last two digits of 31^26 are 81.
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