What does this have to do with personal finance?
Buying stock is a common activity in the realm of personal finance. (Although people are foolish to pay a 2% commission.)
You did learn to multiply in grade school, didn't you? 400 x $102.90 x 1.02
( 400 shares * $102.90/share) * 1.02 = your price
2% is a ridiculously high commission.