The two additional digits can have the values {0, 2, 3, 4, 5, 6, 7, 8, 9} without repeats.
There are 9*8 = 72 possibilities.
3.14 has a finite number of digits. All numbers with a finite number of digits are rational. Pi has an infinite number of digits, AND the digits don't repeat in a regular pattern. (Numbers with repeating decimals are rational as well.)
192, including ones containing repeat digits.
none
If you don't repeat, 20. If you do, 58.
5
3.14 has a finite number of digits. All numbers with a finite number of digits are rational. Pi has an infinite number of digits, AND the digits don't repeat in a regular pattern. (Numbers with repeating decimals are rational as well.)
Irrational numbers.
192, including ones containing repeat digits.
3 decimal digits without repeats can form (10 x 9 x 8) = 720 distinct displays.For each of these . . .3 letters without repeats can form (26 x 25 x 24) = 15,600 distinct displays.Combine them on one plate, and there are (720) x (15,600) = 11,232,000 distinct displays available.
0.076923076923076923076923076923076 ... The digits 076923 repeat over and over.0.076923076923076923076923076923076 ... The digits 076923 repeat over and over.0.076923076923076923076923076923076 ... The digits 076923 repeat over and over.0.076923076923076923076923076923076 ... The digits 076923 repeat over and over.
If you can repeat a digit, there are 27. If you can't repeat a digit, there are only 6.
none
If you don't repeat, 20. If you do, 58.
5
All numbers with a finite number of decimal digits are rational. Some that infinitely many decimal digits are rational as well. If you mean to repeat the pattern, adding one more "1" every time, then no, it is not rational - rational numbers repeat the SAME sequence of digits over and over (for example, 0.1515151515...), at least eventually (they may start with some digits that are not part of the repeating part, such as 3.87112112112...).
Six, if you don't repeat any digits.
9999