hello I need to divide the values of two filds.They are the same fields but have a different record id's is there a way to do it.

Hello,
It's based on two conditions
1)if the type of sample is outside 
2)The type of mold should match for both the records

In general it is very difficult to do more mathematical operations involving different records. But in any event your explanation is far from sufficient to give you an answer. What if there is 1000 records on your table. How was it supposed to know which two records you want to divide.

hello,
I have a table which consists of different mold samples.I have to calculate the failure percentage.To calculate the failure percentage I need divide two fields which are of the same mold but collected in different locations.I hope this is sufficient for my explanation._