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kelsier1569
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kelsier1569
When 2^1/7 leaves a remainder of 2, 2^3/7 leaves a remainder of 1, 2^5/7 leaves a remainder of 4, my question is, when bases raised to odd exponents give different remainder values, how to figure out the pattern? Or even calculate remainders for questions like 2^13/7 or 2^15/7 or 2^131/7 etc?

For example, let’s determine the remainder of the division 2^131/7.

First, we have to explore the repeating remainder pattern:

2^1/7 = 0 remainder 2
2^2/7 = 0 remainder 4
2^3/7 = 1 remainder 1
2^4/7 = 2 remainder 2

We can stop at the first repeating number and conclude that the repeating remainder pattern of 2^k/7 is 2-4-1.

In other words, every third power of 2 will have a remainder of 1 after division by 7.

Since we are looking for the remainder of the division 2^131/7, we find the closest number to 131 that is a multiple of 3. We see that number is 132.

If the question were about the remainder of the division 2^132/7, then our answer would be 1.

However, 131 is one less than 132, so we have to move back one place from 1 in the remainder pattern 2-4-1.

Therefore, the remainder of the division 2^131/7 is 4.

Thank you so much for your time and detailed explanation, Jeff!
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