What is the standard (preferred) way to show a sub-scripted variable raised

to an exponent. I run into these often in my equations, and have a number

of possible solutions, and was wondering what the rest of the world does.

Rob

$V_{infty}^2$

$V_{infty}\,^2$

$V_{infty}\ ^2$

$V_{infty}^{\,2}$

$V_{infty}^{\ 2}$

$V_{infty}^{\ \!2}$ <----possibly my favorite

$V_{infty}^{\ \!\!2}$