111111111 x 111111111 = 12345678987654321

12 3 - 4 5 67 8 9 = 100

1 x 8 1 = 9

12 x 8 2 = 98

123 x 8 3 = 987

1234 x 8 4 = 9876

12345 x 8 5 = 98765

123456 x 8 6 = 987654

1234567 x 8 7 = 9876543

12345678 x 8 8 = 98765432

123456789 x 8 9 = 987654321

The number 142857 is rather special. When you multiply it the digits found in the answer stay the same, just in a different order. Check it out:

1 x 142857 = 142857

2 x 142857 = 285714

3 x 142857 = 428571

4 x 142857 = 571428

5 x 142857 = 714285

6 x 142857 = 857142

What happens when you multiply it by 7? You get another rather special number:

7 x 142857 = 999999

And it doesn't stop there:

142 857 = 999

14 28 57 = 99

142857 x 142857 = 20408122449

20408 122449 = 142857

That’s one amazing number!