$latex 1 \times 9 + 2 = 11$
$latex 12 \times 9 + 3 = 111$
$latex 123 \times 9 + 4 = 1111$
$latex 1234 \times 9 + 5 = 11111$
$latex 12345 \times 9 + 6 = 111111$
$latex 123456 \times 9 + 7 = 1111111$
$latex 1234567 \times 9 + 8 = 11111111$
$latex 12345678 \times 9 + 9 = 111111111$
$latex 9 \times 9 + 7 = 88$
$latex 98 \times 9 + 6 = 888$
$latex 987 \times 9 + 5 = 8888$
$latex 9876 \times 9 + 4 = 88888$
$latex 98765 \times 9 + 3 = 888888$
$latex 987654 \times 9 + 2 = 8888888$
$latex 9876543 \times 9 + 1 = 88888888$
$latex 98765432 \times 9 + 0 = 888888888$
$latex 1 \times 8 + 1 = 9$
$latex 12 \times 8 + 2 = 98$
$latex 123 \times 8 + 3 = 987$
$latex 1234 \times 8 + 4 = 9876$
$latex 12345 \times 8 + 5 = 98765$
$latex 123456 \times 8 + 6 = 987654$
$latex 1234567 \times 8 + 7 = 9876543$
$latex 12345678 \times 8 + 8 = 98765432$
$latex 123456789 \times 8 + 9 = 987654321$