One by one:

//use variables to keep the grade and the total of all grades

float grade1,grade2,grade3,grade4,grade5,grade6,grade7,grade8;

float grade9,grade10, total=0;

// now do it one by one

grade1=ask("enter a grade");

total=total+grade1;

 

grade2=ask("enter a grade");

total=total+grade2;

 

grade3=ask("enter a grade");

total=total+grade3;

 

... hey! can't I do any better?