I need help with debug

Question

Debug06-02
// Program lets user input scores on four tests
// Average is computed and letter grade is determined
// Letter grades are based on 90 for an A, 80 for a B, and so on
start
string name
num score
num NUM_TESTS = 4
num NUM_RANGES = 5
num RANGES[NUM_RANGES] = 90, 80, 70, 60, 0
num QUIT = "ZZZZZ"
string GRADES[NUM_RANGES] = "A", "B", "C", "D", "F"
num total
num average
num sub
output "Enter student name or ", QUIT, " to quit "
input name
while name <> QUIT
sub = 0
while sub < NUM_TESTS
output "Enter score "
input score
total = total + score
endwhile
average = total / NUM_TESTS
sub = 0
while average < RANGES[NUM_TESTS]
sub = sub + 1
endwhile
letterGrade = GRADES[NUM_TESTS]
output name, letterGrade
output "Enter student name or ", QUIT, " to quit "
input name
endwhile
stop

Answer 1

If you need debug help, please
1. specify the compiler/language
2. supply error messages you got when the programme was executed or compiled.
3. indicate if it is a compilation, execution or logical error.

This one looks fishy:
output "Enter student name or ", QUIT, " to quit "

probably should read
output "Enter student name or QUIT to quit "

here:
while sub < NUM_TESTS
output "Enter score "
input score
total = total + score
endwhile

will run forever unless you increment sub.

while sub < NUM_TESTS
output "Enter score "
input score
total = total + score
sub=sub+1
endwhile

letterGrade = GRADES[NUM_TESTS]
means you'll always get an F.
I suggest
letterGrade = GRADES[sub]

Good luck!