What does the 'sum' in vector addition refer to?

[MIA6]

I have a question on 'vector addition'. I know that resultant is the sum of two or more vectors. But this sum doesn't mean the sum of magnitudes of two or more vectors, right? So what does that 'sum' refer to? Combined effect? Hope you can answer my question, thanks.

 

[trajan22]

The sum is the addition of the i, j, and k components of the vector. To find the magnitude of the sum you first need to add the components then find the magnitude of the resultant vector. i.e. take the square root of the sum of the squares.