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Deux Digit Deduction (Posted on 2015-01-21)

X = 9⁹, Y = 9^X and Z = 9^Y

Find the respective last two digits of Y and Z.

See The Solution Submitted by K Sengupta

Rating: 5.0000 (1 votes)

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powerful solution

| Comment 1 of 2

The last two digits of powers of 9 have a cycle of length 10, so you only need the last digit of the exponent to know the last two digits of the power.

Since 9^9 ends in 89
Y also ends in 89
and so
Z also ends in 89.

Posted by Jer on 2015-01-21 12:25:04

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