Where is the error in this code?

Question

https://code.sololearn.com/W5w8w3g1pVw4/?ref=app

Answer 1

1) declare your variables outside the function to make them global.
2) use "clearInterval (...)" to stop function calls

Answer 2

Try to write var av,bv,cv and dv before the functions, but its optional
Then, try
document.getElementById('abcd').innerHTML = av;
Instead of
var a = .....

Answer 3

Because when you write a variable in which you define it's innerHTML, you will get 2 value loops running at the same time like this :
a = 0
av = 5
a = 1
av = 6
a = 3
av = 7
This is what happens when you make it a variable

P.s. sorry if I am not explaining this very understandable because of my poor english skills, but I've only had 2 years of english lessons.

Answer 4

Thanks!