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There are no short cuts to solve these types of questions.
You have to go step wise, uehere for rough idea, you can take 300 in place of 303 to find out nearby answer which wont be always correct if nearby options are present.
Calculate denominator with all the 10 raise to elements taken together or in the numerator, you can reach the answer quickly.
64.91x10 / 25 = 26 so e26