Verbal Reasoning - Arithmetic Reasoning - Discussion
Discussion Forum : Arithmetic Reasoning - Section 2 (Q.No. 30)
30.
A printer numbers the pages of a book starting with 1 and uses 3189 digits in all. How many pages does the book have ?
Answer: Option
Explanation:
No. of digits in 1-digit page nos. = 1x9 = 9.
No. of digits in 2-digit page nos. = 2 x 90 = 180.
No. of digits in 3-digit page nos. = 3 x 900 = 2700.
No. of digits in 4-digit page nos. = 3189 - (9 + 180 + 2700) = 3189 - 2889 = 300.
Therefore No. of pages with 4-digit page nos. = (300/4) = 75.
Hence, total number of pages = (999 + 75) = 1074.
Discussion:
16 comments Page 1 of 2.
Sowmya said:
1 decade ago
I did not understand the procedure from 2nd step. Why did he take 90 in 2nd step?
Rahul Verma said:
1 decade ago
@Sowmya.
Because from 10 -99 there are 90 pages with two digits.
Because from 10 -99 there are 90 pages with two digits.
Chandu said:
1 decade ago
Where from 999 came?
Souvik said:
1 decade ago
No of pages with 1-digit page no=9/1 = 9.
No of pages with 2-digit page no=180/2 = 90.
No of pages with 3-digit page no=2700/3 = 900.
Total no of pages with 1-digit, 2-digit and 3-digit numbers = 9+90+900 = 999.
Required no of pages = 999+75 = 1074.
No of pages with 2-digit page no=180/2 = 90.
No of pages with 3-digit page no=2700/3 = 900.
Total no of pages with 1-digit, 2-digit and 3-digit numbers = 9+90+900 = 999.
Required no of pages = 999+75 = 1074.
Akash said:
10 years ago
9 digits covered in 1-9 pg no.
90*2 = 180 digits covered in 10-99 pg no.
900*3 = 2700 digits covered in 100-999 pg no.
Now 3189-(9+180+2700) = 300 digits will cover in 4 digits pg no.
So 300/4 pages will take to cover 300 nos.
i.e 75. Now total pages will be 999+75 = 1074 pages.
90*2 = 180 digits covered in 10-99 pg no.
900*3 = 2700 digits covered in 100-999 pg no.
Now 3189-(9+180+2700) = 300 digits will cover in 4 digits pg no.
So 300/4 pages will take to cover 300 nos.
i.e 75. Now total pages will be 999+75 = 1074 pages.
Dev Yadav said:
10 years ago
If there is 1242 digits used in all then.
VENKY said:
9 years ago
Excellent.
Dilip Kumar Das said:
9 years ago
Per page 1 digit cover in 1-9 pg no. = 9 digits covered.
Per page 2 digit cover in 10-99 pg no. = 90*2 = 180 digits covered.
Per page 3 digit cover in 100-999 pg no. = 1242 - (9 + 180) = 1053 digit.
Then, 9 digit covered = 9 page.
180 digit covered = 90 page.
1053 digit covered = 1053/3 = 351 page.
Total = 9+90+351 = 450 pages.
Per page 2 digit cover in 10-99 pg no. = 90*2 = 180 digits covered.
Per page 3 digit cover in 100-999 pg no. = 1242 - (9 + 180) = 1053 digit.
Then, 9 digit covered = 9 page.
180 digit covered = 90 page.
1053 digit covered = 1053/3 = 351 page.
Total = 9+90+351 = 450 pages.
Najmi said:
9 years ago
If there is 2736 digits used in all then what is the number of pages?
Sam_91 said:
9 years ago
I did not understand from this step.
Number of digits in 4-digit page nos.
Why don't we calculate 4 digits from 1000 to 3189?
Number of digits in 4-digit page nos.
Why don't we calculate 4 digits from 1000 to 3189?
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers