#1 = 1/3
#2 = 5/6
#3 = 8/9
#4 = 6/7
#5 = 15/20
Let say the number is 0.5
Then, sum of this number will be 0.5+0.5=1
Now two is twice of 1.
Hence, it proved to be correct.
And difference between 5 and 1 is 4 which is less than 12. It also match the question condition.
Answer: The number is 1.

Rounded to the tenth: 3.3
Square roots that are not perfect squares are always
irrational