Ok stop a minute.

There are two ways to do this

Put your formula in D1. it works right?

Now move your cursor to the bottom right corner of D1

The cursor will change to a small + with no arrow heads.

now left click and drag tour cursor down to D10 and release the left mouse button.

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Put your formula in D1 it works right?

select D1, left click and move your cursor down to D10

release the left button

Click into the formula bar click at the end of the formula and press ctrl and then enter together