A certain street contains 100 buildings.They are numbered from 1 to 100. How many 9s are used in numbering these buildings? Choose the most appropriate option.
A) 21 B) 20 C) 19 D) 18 E) 9
9,19,29,39,49,59,69,79,89,90,91,92,93,94,95,96,97,98,99   so number of 9's=20   ANSWER:20
<result>B</result>
A certain street contains 100 buildings.They are numbered from 1 to 100. How many 9s are used in numbering these buildings?