how to calculate the sum of the values of some columns of a table

[achfire]

ok

[crossrulz · Accepted solution]

I'm willing to bet that you put something in the third row.  Even if it was deleted, there will be an empty string.  And since arrays must be rectangular, if you added to row 2 anything, all of the colums will have something in there.  They will default to an empty string.  And when you convert an empty string to a number, you get 0 (whatever you specify as the default).  So the added 0s throw off your average.

So put in some code to filter out the empty strings to that they don't affect your average.

[achfire]

really thanks a lot P@Anand and crossrulz for your precious help 😉