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 2 of 2.
Abid ali said:
8 years ago
Because 1 digt page no. is 9 and 2 digts pages no. is 90 and 3 digits pages no. is 900.
So, total number page digits 1,2&3 are 2889.
Then, rest pages will be 4 digits these are 300.
Thus we calculate 300/4 and get 75 pages.
So, total number page digits 1,2&3 are 2889.
Then, rest pages will be 4 digits these are 300.
Thus we calculate 300/4 and get 75 pages.
(1)
Zarith said:
8 years ago
Why do we divide 300 by 4? I don't understand. Please explain it.
Payal said:
7 years ago
Why do we divide 300 by 4? Please explain.
Basant bhatt said:
4 years ago
Why do we divide 300 by 4? I don't understand. Please explain.
Dileep said:
3 years ago
@All.
Know the difference between digit and number before solving this question.
Hope the below example helps you.
Consider a book of 5 pages, then the total number of digits of all pages is 5 i.e. 1, 2, 3, 4, 5 (1+1+1+1+1=5).
Now, consider a book of 10 pages, then the total number of digits of all pages is 11 i.e.1, 2, 3, 4. 10 (1+1+1+1+1+1+1+1+1+2=11) since the number 10 has 2 digits.
Now, coming to the question. The total digits the printer uses is 3189 (not numbers, just digits).
No Of 1 digit pages =9 (1 to 9) , digits =9.
No Of 2 digit pages = 90 (10 to 99) , digits = 180 (since each number has 2 digits).
No Of 3 digit pages = 900 (100 to 999) , digits = 2700.
Now, to calculate the no. Of 4 digit pages, calculate the remaining digits.
3189 - (9 + 180 + 2700) = 3189 - 2889 = 300.
These 300 are digits for 4-digit pages. That means the printer will print 4 digits on each page.
No Of 4 digit pages = 300/4 = 75 (each page has a 4 digit number).
Now, total no. Of pages = 9 + 90 + 900 + 75 = 1075.
Know the difference between digit and number before solving this question.
Hope the below example helps you.
Consider a book of 5 pages, then the total number of digits of all pages is 5 i.e. 1, 2, 3, 4, 5 (1+1+1+1+1=5).
Now, consider a book of 10 pages, then the total number of digits of all pages is 11 i.e.1, 2, 3, 4. 10 (1+1+1+1+1+1+1+1+1+2=11) since the number 10 has 2 digits.
Now, coming to the question. The total digits the printer uses is 3189 (not numbers, just digits).
No Of 1 digit pages =9 (1 to 9) , digits =9.
No Of 2 digit pages = 90 (10 to 99) , digits = 180 (since each number has 2 digits).
No Of 3 digit pages = 900 (100 to 999) , digits = 2700.
Now, to calculate the no. Of 4 digit pages, calculate the remaining digits.
3189 - (9 + 180 + 2700) = 3189 - 2889 = 300.
These 300 are digits for 4-digit pages. That means the printer will print 4 digits on each page.
No Of 4 digit pages = 300/4 = 75 (each page has a 4 digit number).
Now, total no. Of pages = 9 + 90 + 900 + 75 = 1075.
(2)
Dileep kumar said:
3 years ago
@Najmi.
Here is the answer.
1 to 9 = 9.
10 to 99 = 90.
The remaining 2736-(180+9) = 2547 (all these digits as printed as 3 digit numbers).
100 to x = 2547/3 = 849.
total pages = 9 +90 + 849 = 948 pages.
Here is the answer.
1 to 9 = 9.
10 to 99 = 90.
The remaining 2736-(180+9) = 2547 (all these digits as printed as 3 digit numbers).
100 to x = 2547/3 = 849.
total pages = 9 +90 + 849 = 948 pages.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers