What repeating decimal is equal to 4?

Question

I think it is 3.999
Am I Wrong? Help Please

Answer 1

That should work.
3.99999.....

3 + 9/10 + 9/100 + 9/1000 .....

3 + 9/10

3 + geometric sequence
3 + a + ar + ar^2 ...
3 + 9/10 + 9/10(1/10)etc
a = 9/10
r = 1/10

sum = (9/10) (1/.9)
so
3 + sum of infinite geometric series
where a = .9
r = .1

Answer 2

Thank you(: