The correlation coefficient between the company's online ad spend and sales revenue is approximately $0.995$. This indicates a very strong positive linear relationship between the two variables.

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Here are some related questions:

1. What is the significance of a correlation coefficient close to 1?
2. Can we predict future sales revenue based on this data?
3. How would a correlation coefficient of 0 or -1 affect the relationship?
4. What other factors could influence sales revenue besides ad spend?
5. How can we calculate a regression equation using this data?

Tip: A high correlation does not always imply causation; further analysis is often necessary to determine the nature of the relationship.