Simple Formula not working?

[GETGO]

I did a simple formula like adding 40 five times in a column. I used the sum formula and then changed a 40 to a 0 and the total did not change. The same is happening with all my formulas. The first time I create the formula it works but when I change a number it does not recalulate. Does anyone know what the problem is?

[Cutter]

Go to Tools>Options>Calculation tab

Make sure the "Automatic" option is chosen instead of the "Manual"

[GETGO]

Cutter, that was the problem. Thanks so much for your help....