Click the handle of the balloon pump to fill the air in the balloon,the size is how much you filled.100 is full For a challenge,You can press z to make the size variable disapear and X to make it re-apear
A little note: when you get the size is 100 and it hides but does not show and pump it it will not show for the next time you pump because you were not patient.Get it to 100 again and wait. Another note: if you pump the handle while it is popped it will just increase another 3 secs of your time