how many integers between have tens digit 1 and unit digit 3 ?

[blover]

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[ibelieveican]

Good Q
IMO E

Here is how.
324700 to 458600

Let us consider intervals now

1. 324a13 what are the values a can take. 7, 8, 9 so 3C1
2. 32ab13 a can take values 5, 6, 7, 8, 9 ( 4 is already considered in 1) 5C1
b can take values from 0 to 9 so 10C1....5c1X10C1
3. 3abc13.. a takes values 3 to 9 so 7C1 b and c takes values 0 to 9 so... 7C1X10C1X10C1

now we need to do the same thing with 458600 and I get E

Hope I made sense

[saketbansal]

458513 - 324713 = 133800
133800 / 100, as only one digit per humdered 1338 +1 as the ending number is also included.
1339
E.

[hawk007]

The questions says we need to find no of XXXXX13 between 324700 to 458600

for every hundred we can only have one 13 so if we calculate no of hundreds between 324700 to 458600 we get the solution

I.e is 458600-324700=133900

divding by 100
we 1339

answer-E

[ibelieveican]

Great approach guys..