Math Trivia : Integers not including 7

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In integers from 1 to 3000, find the number of figures that do not use number 7.


2,187

There are eight in 1~9. 

There are 8 × 9 = 72 in 10 ~ 99. 

There are 8 × 9 × 9 = 648 in 100 ~ 999. 

There are 1 × 9 × 9 × 9 = 729 in 1000 ~ 1999. 

There are 729 in 2000 ~ 2999, too. 

There is one which is 3000. 

There are 8 + 72 + 648 + 729 × 2 = 2,187 in total.