Nine of them
It is any one of infinitely many numbers of the form 1407.92nnn where nnn... is any string of digits other than all 0s or all 9s.
79
They can. And if you include repeating 0s and repeating 9s, then all rational numbers can be written with infinitely long repeating digits.
Eleven.
There are 27 of them.
Only 1 exists, and it is "999"
A repeating decimal is a rational number. Its value is(the repeating set of digits)/(as many 9s as there are digits above).
The first 4 digits after the decimal point must be zero and the next digit must be 4 or smaller. If it is 4, then the subsequent digits cannot be a sequence of repeating 9s.
The answer depends on what the ellipses represent. If it is repeating 9s then it is. If it means that the string of digits goes on but with no repeating pattern then it is not.
Well, honey, if you want to write 0.81 repeating as a fraction in simplest form, you just gotta remember your high school math. It's 81 over 99, because that repeating decimal is 81 over 99. And if you want to simplify it, just divide the top and bottom by 9 to get 9 over 11. Voilà!
There are 70,674 3's in the first million digits of pi. * * * * * There are 100,230 3s and 100,106 9s. Since the decimal representation of pi is essentially random, the number of times any digit appears should be approximately 10% of the total number of digits. So, for a million digits, there should be around 100,000 of any digit so it should have been immediately apparent that the previous answer was extremely unlikely. In fact it was incorrect to a very large degree!
5
There are 8 nines in 72. This can be calculated by dividing 72 by 9, which equals 8. In other words, 9 goes into 72 eight times without any remainder.
Nine of them
It is any one of infinitely many numbers of the form 1407.92nnn where nnn... is any string of digits other than all 0s or all 9s.
79