Thank you for reading the post.

I am trying to use the excel function "SUMPRODUCT" to calculate the sum of products of two sequences. The appeared answer is an extremely small number(2.78E-17), given that I already know the answer is zero.

I do not understand why the answer is not zero. Can anyone help me?

The two sequences are:

1. Probability Sequence: [0.04, 0.08, 0.08, 0.08, 0.08, 0.04, 0.08, 0.08, 0.08, 0.04, 0.08, 0.08, 0.04, 0.08, 0.04], stored in B2:B16.
2. Value Sequence: [-4, -3, -2, -1, 0, -2, -1, 0, 1, 0, 1, 2, 2, 3, 4], stored in C2:C16.

The formula of the answer cell: =SUMPRODUCT(B2:B16, C2:C16).

The shown answer: 2.78E-17

The Correct answer: 0

The print screen of the excel file is attached below:

1. Print screen showing the formula of the cell.
2. Print screen showing the excel spreadsheet.