If you take a Lotto sequence and add up all the numbers, then the answer will be the sum value. An example would be if you take the Lotto sequence 03-12-21-29-38-48, then the sum will be 151.
03 + 12 + 21 + 29 + 38 + 48 = 151

Basically the sum value is useful as you can look at past Lotto sequences and get and idea as to the minimum and maximum sum limits.

Go look at the "Lotto Number Analysis" page and look at the Sum section as to get an idea what sums your Lotto numbers should add up to.

Alternatively you can search for sums of past Lotto sequences using the "Statistics" page. This can be an advantage as you can then see which sums came up more than others.

But this is only one section when it comes to selecting the all elusive winning Lotto numbers/sequence. So please look at other Lotto Game Play articles as well.