Answers

2015-05-24T23:10:10+05:30
In the 500s, 600s, 700s, and 900s, 1 in every group of 10 (except the 80s) has one 8 in it. In the 80s of each of those, 9 have one 8, except the -88s. So here, (1 x 9) + (9 x 1) = 18. Multiply 18 by how many groups of 100 there are (4) and you have 72. 

In the 800s, 9 of every 10 (except the 80s, and except the --8) have one 8. There are also 9 groups of 10 within the 800s, so 9 x 9 = 81. 

Add the two together, and you have 153.
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