Question: how many numbers between 1 and 100 contain the digit 8?
Answer: Every ten series has one 8 and there are in total ten series, so there are 10 for now. However, the series of 80 has 10 eights not including 80. ( 88 has two 8 digits) Therfore, the 8 digit occur in total 20 times between 1 to 100.