You can count up the variable I from 1 to A with FOR/NEXT command. You can get the 5 '*' marks.
Let's modify to use the number you like with INPUT command.
Type any numbers!
Add a number and loop!
You can do the multiplication!
Count variable C that counts number of '*' marks.
C=C+A cause you can get A x '*' marks every loops. Using LET C,C+1 is OK also. If you don't input C=0 or LET C,0, then C will increase in every executions continuously.
Let's try
1. Calculate 7 multiply by 8
2. Calculate 8 multiply by 7
3. Change to the mark that you like
4. Check to change the mark to 2 letters
5. Check if input zero