Jump to content
Urch Forums

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


blover

Recommended Posts

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

Link to comment
Share on other sites

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

 

ANS-E

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...