Excel function showing in the cell instead of the result

[Ellen_Kerns]

I am trying to do a simple SUM of a column of numbers, which I have done many times before without a problem, but this time the SUM function is showing up in the cell instead of the result.  How do I get the result to show instead?

[#2]

@Ellen_Kerns 

1) If the number format of the cell is set to Text, change it to General or Number, then press F2 to edit the formula and press Enter without changing anything.

2) Otherwise, activate the Formulas tab of the ribbon. If the Show Formulas button in the Formula Auditing group is highlighted, click it to turn it off.

[#3]

Your second suggestion was spot-on! Thanks so much for the help!!