19. Andrey found the product of all numbers from 1 to 11 inclusive and wrote the result on the board. During the break, someone accidentally erased three digits, and the remaining number on the board is $399 * 68 * *$. Help restore the digits without recalculating the product.
19. The two rightmost digits are zeros, since among the factors there is the number 10 and also $2 \cdot 5=10$. The product of numbers from 1 to 11 is divisible by 9, 
therefore the sum of the digits of the result must be divisible by 9. The sum of the known digits is $3+9+9+6+8=35$. The number greater than 35 and closest to it that is divisible by 9 is 36. Therefore, the unknown digit is 1.