How to correctly calculate the amount if some cells contain N/A?

Question

excel

I want to calculate the sum of the values ​​of column C.
There is a formula for column C: =ВПР(B2;$J$3:$K$5;2;ЛОЖЬ)
For those cells where values ​​have not yet been specified, the formula does not work and N/A is indicated.
Because of this, I can not calculate the SUM of the entire range.

Answer 1

Wrap the result in the formula IFERROR
It turns out like this:
=IFERROR(VLOOKUP(B2,$J$3:$K$5,2,FALSE); 0)
If the value is calculated correctly, it will be displayed. If the result is N/A, it will be replaced with 0