Completing the condition of the DO WHILE

Now the program looks like:

'
' Do something or other until a 
' sentinel value is entered
'
PRINT "Enter first number"       
INPUT NUMBER                 
'
DO WHILE ... number is not a sentinel value ...
  PRINT SQR ( NUMBER )
  PRINT "Enter the next number."       
  INPUT NUMBER                 
LOOP
PRINT "Bye"
END

QUESTION 18:

We want execution to enter the loop body when NUMBER is positive or zero. Finish the last blank of the program:

... number is not a sentinel value ...

so the program will be complete.