9, 9, 19, 29, 39, 49, 59, 69, 79, 89, 99, 1 1 9 (99 has two 9s).

Ten nines are 90, 9 1, 92, 93, 94, 95, 96, 97, 98(99 has appeared) and nine nines.

So there are 20 9s in a * * *.

Extended data

1, arithmetic of addition and subtraction

Integers are aligned with the same number of digits, starting with single digits. When adding up to ten digits, high digits will be entered; If the subtraction is not enough, subtract 1 from the high position. When this number is added to 10, it will decrease.

2. Multiplication algorithm

Integer is multiplied from the unit, and the first factor is multiplied by the number on each bit of the second factor in turn; Multiply by the number on the second factor, and the last digit of the number will be aligned with the second factor; Add the multiplied numbers several times;

3, the algorithm of division

Integer is divided by the high order of dividend; How many digits is the divisor? Look at the first few digits of the divisor first. If the divisor is not enough, look at one more digit. In addition to which one, you must write your business on which one; The remainder of each division must be less than the divisor; After finding the highest bit of quotient, if the dividend is not quotient 1, write 0 on it;