accumulated one row

[linbai]

I want accumulated  row 'nb' like this:

how to make it ?

thank u ...

[BigChris]

Have you tried running_total() ?

[linbai]

Have you tried running_total() ?

thank u for your reply
yes,I have  already tried, but the number is wrong. the row 'test' shoud be  2393  3775 4799 ....

[linbai]

Have you tried running_total() ?

thank u so much ! !