Question

When writing numbers from 1 to 10,000, how many times is the digit 9 written? (HINT: Count the ‘9’s in the range 1- 100 then use it to count the ‘9’s in the range 1- 1000 and then the range 1- 10000 )

Answer 1

Answer:

4,000

Its simple counting ig

Answer 2

The Number of 9 in each series.

1-100- 20's 9

101-1000- 160's 9 and 120's 9

1-1000- 300's 9

1001-8999- 2400's 9

9000-10000- 1300's 9

The total number of 9 in 1-10000 is,

$(1-1000)+(1001-8999)+ (9000-10000)=300+2400+1300\\=4000$

4000's 9 are there in the counting of 1-10000.

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