Copying cell formula with a constant formula value

I need help please filling all my excel table cells with the following formula that is placed in E10 cell:

=(1000-E9)*D10

So when I copy the above cell formula horizontally the E9 should be replaced with F9 in the next cell and G9 in the cell after and so on in accordance with the horizontal cell respective letter along the reaming horizontal cells however D10 in the formula should remain fixed as (D10).
And when copying E10 cell formula vertically, cell E9 in the formula should stay fixed as (E9) and the D10 should change to D11 in the next cell and D12 in the cell after and so on in accordance with the vertical cell respective number along the reaming vertical cells.