"I mean if the answer comes out to be 0.645480000 can we limit it to two digits after decimal like 0.64?"
Be aware that "formatting" that answer to show only two digits after the decimal does not change the value contained in the cell. Any calculation done with the number in that cell will use 0.645480000, not 0.64 (and not 0.65, which is what will be displayed if you follow the instructions provided by MobileBlues.
If you want to change the actual value in the cell, you will need to use ROUND, ROUNDDOWN, ROUNDUP or TRUNC, depending on the result you want.
Here's a list of examples. Replace 0.645480000 with the formula used to get that result.
ROUNDUP(0.645480000,2) = 0.65
ROUND(0.645480000,2) = 0.65
ROUNDDOWN(0.645480000,2) = 0.64
TRUNC(0.645480000,2) = 0.64
Regards,
Barry