Question about memory usage in excel

[lars1565]

I have a grade book for a school. It is shared online for teachers and staff to use/edit. Due to the number of formulas it can get kind of bogged down. So I am looking to save some processing power and accomplish the same task.
A teacher enters a percent in cell then the cell below has a large formula to calculate the letter grade associated with that percent. So each cell has a big formula for each student and each of their classes.
I am wondering if I switch from: =IF(F1405>=0.93,"A",IF(F1405>=0.9,"A-",IF(F1405>=0.87,"B+",IF(F1405>=0.83,"B",IF(F1405>=0.8,"B-",IF(F1405>=0.77,"C+",IF(F1405>=0.73,"C",IF(F1405>=0.7,"C-",IF(F1405>=0.67,"D+",IF(F1405>=0.63,"D",IF(F1405>=0.6,"D-",IF(F1405="","","N"))))))))))
to: a short lookup() formula with a table that has percent and associated grades. Would that use less memory and run faster?

Thanks

 

[shg]

	A​	B​	C​
1​	Score​	Grade​	​
2​	95%​	A	B2: =IF(A2="", "", LOOKUP(A2, {0,60,63,67,70,73,77,80,83,87,90,93}%, {"N","D-","D","D+","C-","C","C+","B-","B","B+","A-","A"}))
3​	92%​	A-
4​	87%​	B+
5​	86%​	B
6​	81%​	B-
7​	78%​	C+
8​	72%​	C-
9​	68%​	D+
10​	64%​	D
11​	62%​	D-
12​	59%​	N

 

[Dave Patton]

The following is just shg's suggestion with a table for the Lookup.

Excel 2010
	A	B	C	D
1	Score	Grade	Grade	Grade
2	95%	A	A	A
4b

Cell Formulas
Range	Formula
B2	=IF(A2="", "", LOOKUP(A2, {0,60,63,67,70,73,77,80,83,87,90,93}%, {"N","D-","D","D+","C-","C","C+","B-","B","B+","A-","A"}))
C2	=LOOKUP(A2,$E$1:$F$12)
D2	=LOOKUP(A2,rGrades)

Named Ranges
Name	Refers To	Cells
rGrades	='4b'!$E$1:$F$12

 

[shg]

Your current formula and all of the alternatives should be lightning fast. I'd be inclined to use Dave's suggestion to put the lookup data in a table -- just be aware that you you change the table (like you decide to start grading on a curve), it will change all of the grades, some perhaps unintendedly.

 

[Dave Patton]

Hopefully, the suggested formula helps.

Once the grades are calculated, the information may be static;
consequently, the formula results could be converted to values.

With about 1050 students, the file with the formulas is just 70k.
The file with all rows as values except the first row of calculations is just 54K.

Your file may include other calculations or statistics that are resource intensive.

Excel 2010
	A	B	C	D	E
1	Name	Score	Grade	Grade	Grade
2	A1233	95%	A	A	A
3	A1234	92%	A-	A-	A-
Sheet1

Cell Formulas
Range	Formula
C2	=LOOKUP(B2,$F$1:$G$12)
D2	=LOOKUP(B2,rGrades)
E2	=LOOKUP(B2,rGrades)

Named Ranges
Name	Refers To	Cells
rGrades	=Sheet1!$F$1:$G$12