Make a number of all the digits 1 to 9 leaving out 8 :
12 345 679
Now, multiply it first by any single-digit numbers : (say for instance 5)
12 345 679 x 5 = 61 728 395
Multiply the product by 9.
61 728 395 x 9 = 555 555 555
YOU SHOULD GET YOUR SINGLE-DIGIT BACK NINE FOLD.
