conditional formatting with empty cells

[haiching]

I am creating the attached engineering chart and want to have empty rows in it for future use (row 16), however the calculations effect other cells, like C21.
What should the formula be to allow these empty rows?
Appreciate any help!
thanks

[sktneer]

Hi,
Welcome to the forum.

Try this....

In C4

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and copy down.

In F4

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and copy down.

In G4

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and copy down.

Does this help?