PDF time sheet using FormCalc or JavaScript to calculate hours worked

Question

I'm trying to create a timesheet that will calculate the hours an employee worked. There is 4 In columns and 4 Out columns that I need to total the hours (see below).

In 0830 Out 1200 In 1300 Out 1700 In ------ Out -----

Needs to total 7.5 hours worked

If I use (OUTA1[0]-INA1[0])/100+(OUTA1[1]-INA1[1])/100+(OUTA1[2]-INA1[2])/100 I get 7.7

If I use (OUTA1[0]-INA1[0])/100+(OUTA1[1]-INA1[1])/100+(OUTA1[2]-INA1[2])/100-.2 I get 7.5 but does not work when the hours are

In 0800 Out 1200 In 1300 Out 1700 In ------ Out -----

Any help would be greatly appreciated.