How to use Eng Notation on QTGUI Vector Sink?

Good day!!!

I’m trying to use the eng notation in a QTGUI Vector Sink but I don’t
know how. I’m getting spectrum information and I have data around
9.97E08 but I would like to display that information like this: 9.97M.

Is there any way to get the eng notation in the ploted graphic?

Thank you.