What does a number in gradient symbol subscript means? 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 ? !enter image description here What does that 3 means ? It is multiplied three times ?

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

Sometimes $\
abla$ 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.