7^1 by 100 leaves a remainder of 7.
7^2 by 100 leaves a remainder of 49.
7^3 by 100 leaves a remainder of 43.
7^4 by 100 leaves a remainder of 1.
7^5 by 100 leaves a remainder of 7.
7^6 by 100 leaves a remainder of 49.
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.now…we have a repeating sequence with us, where the remainder is repeating for every 4 number’s…that’s 7^1 and 7^5 leaves the same remainder….
Coming to the answer…using this as the base 7^2 and 7^98 are the same.
hence 7^4 and 7^100 will have the same remainder as 1.
hence the solution to your answer is 1.