Puzzle "Bigger Value"

Level (Easy)

The teacher wanted to test the intelligence of his students. He told them to give me examples of numbers

Consists of 4 cells to the maximum extent, when rotated to a certain degree clockwise

It produces greater value.

The first student said: The number 6 turns 180 degrees, the value increases to 9.

While the second student said: I have a bigger example of the increase, the number 6996

A 180 degree rotation also produces 9669 and a significant increase!

The third student struck an insurmountable example

What is it?