What does a number in gradient symbol subscript means?

Question

While solving some problems I have encountered a subscript in front of a gradient symbol. I'm unable to understand it, I know a superscript of 2 on gradient symbol means Laplacian but what does subscript means ?

Can anyone explain ?

What does that 3 means ? It is multiplied three times ?

Answer 1

The Laplacian is represented with a superscript 2, not a subscript.

Sometimes $\nabla$ can represent a vector (or matrix) of derivatives which can prove a useful shorthand, as in here for example.

Do you have a specific example you can provide? Perhaps some context would help.

Answer 2

The "del" $\nabla$ symbol is an abbreviation for "derivative," so such a symbol with a subscript three means that all the "arguments" of the function (in parentheses) are taken to the third derivative.