9 × 9 + 7 = 88
98 × 9 + 6 = 888
987 × 9 + 5 = 8888
9876 × 9 + 4 = 88888
98765 × 9 + 3 = 888888
987654 × 9 + 2 = 8888888
9876543 × 9 + 1 = 88888888
98765432 × 9 + 0 = 888888888

03/30/2017 UPDATE: Reader Alon Shaham points out that:

987654321 × 9 – 1 = 8888888888
9876543210 × 9 – 2 = 88888888888