Q: Using checkbox in Numbers to add/subtract a value of 0.5

Hi,

I am using a formula that calculates daily work hours and subtracts half an hour for lunch if a checkbox is checked. The formula works except for the 0.5 hour being added or subtracted. Any ideas? The checkbox works to subtract the boolean value (0 or 1), I just need this value to be represented as 0.5 if you get my drift....

Thanks in advance!