Mandy took a math quiz and received an initial score of i. She retook the quiz several times and, with each attempt, doubled her previous score.
After a total of four attempts, her final score was ________.

The correct answer is: 2³i

Any of various mathematical operations that are analogous in some way to multiplication of the real numbers but are defined for other or larger sets of elements (such as complex numbers, vectors, matrices, or functions)
Mandy took a math quiz and received an initial score of i
Second time Mandy took quiz and then received 2i it is double of first received
Third time Mandy took quiz and then received 2×2i=4i it is double of previous.
So, thus 2×4i=8i Mandy received 8i in fourth attempt.
Or,
Her first score was i. She doubled the previous score three times or 2³i.

The multiplication formula is expressed as, Multiplicand × Multiplier = Product;
Multiplication is an operation that represents the basic idea of repeated addition of the same number. The numbers that are multiplied are called the factors and the result that is obtained after the multiplication of two or more numbers is known as the product of those numbers.