believe it or not i dont have e-mail access right now, but if you enter the formula i provided into cell I2 of your sample sheet you should get the result.

then you can copy down to your other rows, but you will need to adjust the range $B$14:$B$814 to the next range as well ($C$14:$C$814) and so on.

also you should not post your e-mail on public forums, as they are easily searched / scaned by spamers.