Last visit was: 18 Jun 2025, 02:18 It is currently 18 Jun 2025, 02:18
Close
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Close
Request Expert Reply
Confirm Cancel
User avatar
GMATinsight
User avatar
Major Poster
Joined: 08 Jul 2010
Last visit: 18 June 2025
Posts: 6,344
Own Kudos:
15,454
 [18]
Given Kudos: 128
Status:GMAT/GRE Tutor l Admission Consultant l On-Demand Course creator
Location: India
GMAT: QUANT+DI EXPERT
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
WE:Education (Education)
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
Posts: 6,344
Kudos: 15,454
 [18]
Kudos
Add Kudos
18
Bookmarks
Bookmark this Post
User avatar
nick1816
User avatar
Retired Moderator
Joined: 19 Oct 2018
Last visit: 17 Jun 2025
Posts: 1,853
Own Kudos:
7,731
 [1]
Given Kudos: 707
Location: India
Posts: 1,853
Kudos: 7,731
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
Archit3110
User avatar
Major Poster
Joined: 18 Aug 2017
Last visit: 17 Jun 2025
Posts: 8,239
Own Kudos:
4,742
 [1]
Given Kudos: 243
Status:You learn more from failure than from success.
Location: India
Concentration: Sustainability, Marketing
GMAT Focus 1: 545 Q79 V79 DI73
GPA: 4
WE:Marketing (Energy)
GMAT Focus 1: 545 Q79 V79 DI73
Posts: 8,239
Kudos: 4,742
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
avatar
fireagablast
Joined: 30 Jun 2019
Last visit: 17 Aug 2021
Posts: 265
Own Kudos:
Given Kudos: 8
Posts: 265
Kudos: 117
Kudos
Add Kudos
Bookmarks
Bookmark this Post
nick1816
Number of digit 3's which we use while writing all distinct integers from 000 to 999 is (3*1000)/10 = 300.

Their sum = 3*300=900

Why do you divide by 10?
Can you actually explain the logic behind this approach? Thank you
User avatar
GMATinsight
User avatar
Major Poster
Joined: 08 Jul 2010
Last visit: 18 June 2025
Posts: 6,344
Own Kudos:
15,454
 [4]
Given Kudos: 128
Status:GMAT/GRE Tutor l Admission Consultant l On-Demand Course creator
Location: India
GMAT: QUANT+DI EXPERT
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
WE:Education (Education)
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
Posts: 6,344
Kudos: 15,454
 [4]
2
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
GMATinsight
Find the sum of all the digits '3', which we use while writing all distinct integers from 1 to 1000?

A) 300
B) 600
C) 813
D) 900
E) 930

Source: https://www.GMATinsight.com


Answer: Option D

Check the video explanation here

User avatar
EgmatQuantExpert
User avatar
e-GMAT Representative
Joined: 04 Jan 2015
Last visit: 02 Apr 2024
Posts: 3,681
Own Kudos:
19,319
 [1]
Given Kudos: 165
Expert
Expert reply
Posts: 3,681
Kudos: 19,319
 [1]
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
Given

    • All distinct integers from 1 to 1000 are written.

To Find

    • Sum of all the ‘3’ used.

Approach and Working Out

    • We can visualize each number from 0 to 999 as a three digit number XYZ.
      o 0 can be visualized as 000
      o 1 as 001 and so on.
    • Here, we are not biased and using each digit equal number of times.
      o Hence total digit used = 3 × 1000
      o No of 3s used = 3 × 1000/10 = 300
      o Sum = 300 × 3 = 900


Correct Answer: Option D
User avatar
nick1816
User avatar
Retired Moderator
Joined: 19 Oct 2018
Last visit: 17 Jun 2025
Posts: 1,853
Own Kudos:
7,731
 [1]
Given Kudos: 707
Location: India
Posts: 1,853
Kudos: 7,731
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Total number of digits we use from 000 to 999 = 3*1000=3000

Since we covered all possible combinations of 3-digits from 000 to 999, the probability of using each digit must be equal. As we are interested in counting 1 digit outta 10, we gotta divide 3000 by 10.

fireagablast
nick1816
Number of digit 3's which we use while writing all distinct integers from 000 to 999 is (3*1000)/10 = 300.

Their sum = 3*300=900

Why do you divide by 10?
Can you actually explain the logic behind this approach? Thank you
User avatar
Abhineetegi
Joined: 04 Jan 2018
Last visit: 06 Jul 2021
Posts: 36
Own Kudos:
Given Kudos: 100
Posts: 36
Kudos: 31
Kudos
Add Kudos
Bookmarks
Bookmark this Post
EgmatQuantExpert
Given

    • All distinct integers from 1 to 1000 are written.

To Find

    • Sum of all the ‘3’ used.

Approach and Working Out

    • We can visualize each number from 0 to 999 as a three digit number XYZ.
      o 0 can be visualized as 000
      o 1 as 001 and so on.
    • Here, we are not biased and using each digit equal number of times.
      o Hence total digit used = 3 × 1000
      o No of 3s used = 3 × 1000/10 = 300
      o Sum = 300 × 3 = 900


Correct Answer: Option D


Does this method is valid for all digits , other than 3 ?
avatar
Shobhit7
Joined: 01 Feb 2017
Last visit: 29 Apr 2021
Posts: 241
Own Kudos:
395
 [1]
Given Kudos: 148
Posts: 241
Kudos: 395
 [1]
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
From 000 to 999, we have three slots: units / tens / hundreds
For each slot, we have 10 options (digits 0 to 9)
So, total digits = 10*10*10 = 1000

Now, lets fix one slot with digit 3:
unit digit slot fixed as 3, options for tens slot- 10 (0-9) and options for hundreds slots- 10 (0-9). Total numbers 1*10*10= 100
Similarly, when tens and hundreds digit slots are fixed as 3, we will have 100 numbers for each.

Therefore, total number of times digit 3 is repeated in each slot is 100 and total numbers created are 300.

Sum= 3*300 = 900
Ans D
avatar
TarunKumar1234
Joined: 14 Jul 2020
Last visit: 28 Feb 2024
Posts: 1,108
Own Kudos:
Given Kudos: 351
Location: India
Posts: 1,108
Kudos: 1,335
Kudos
Add Kudos
Bookmarks
Bookmark this Post
We need to fix location of 3 and can get how many times 3 called. Please note, we have 3 place for 3 only.

1) 3 at first place then 1*10C1 * 10C1 = 100
2) 3 at 2nd place then 10C1 * 1 * 10 C1 = 100
3) 3 at 3rd place then 10C1 * 10C1 * 1 = 100

So, 3 occurs between 1 to 1000 = 100+100+100 = 300 times. Hence, Sum of 3 occurs= 3*300 = 900 (Ans.)

D
User avatar
EgmatQuantExpert
User avatar
e-GMAT Representative
Joined: 04 Jan 2015
Last visit: 02 Apr 2024
Posts: 3,681
Own Kudos:
19,319
 [1]
Given Kudos: 165
Expert
Expert reply
Posts: 3,681
Kudos: 19,319
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Abhineetegi
EgmatQuantExpert
Given

    • All distinct integers from 1 to 1000 are written.

To Find

    • Sum of all the ‘3’ used.

Approach and Working Out

    • We can visualize each number from 0 to 999 as a three digit number XYZ.
      o 0 can be visualized as 000
      o 1 as 001 and so on.
    • Here, we are not biased and using each digit equal number of times.
      o Hence total digit used = 3 × 1000
      o No of 3s used = 3 × 1000/10 = 300
      o Sum = 300 × 3 = 900


Correct Answer: Option D


Does this method is valid for all digits , other than 3 ?

Hi Abhineetegi,

    •Yes, you can do the same for other digits as well.
    •You just need to multiply 300 by that digit.

    •Please note, the number of all the digits will remain the same for the range 000 to 999.
      oOnly exception is 0 as you understand that we will have counted 0 in 000 or 001 and so on.
      oThese are obviously invalid
User avatar
CoinTheory
Joined: 05 Nov 2024
Last visit: 17 Jun 2025
Posts: 4
Given Kudos: 45
Location: United States
GMAT Focus 1: 675 Q86 V85 DI79
GMAT Focus 1: 675 Q86 V85 DI79
Posts: 4
Kudos: 0
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Why can't we do: [1000 - (all the numbers that dont contain 3)]? 9*9*9

= 271 --> 271*3

This is why I ended up choosing (c)
User avatar
Kinshook
User avatar
Major Poster
Joined: 03 Jun 2019
Last visit: 17 Jun 2025
Posts: 5,612
Own Kudos:
Given Kudos: 161
Location: India
GMAT 1: 690 Q50 V34
WE:Engineering (Transportation)
Products:
GMAT 1: 690 Q50 V34
Posts: 5,612
Kudos: 5,095
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Find the sum of all the digits '3', which we use while writing all distinct integers from 1 to 1000?

Since all digits are used equally between 1 & 1000
Number of digits '3' = 3*1000/10 = 300

Sum of digits '3' = 3*300 = 900

IMO D
User avatar
Krunaal
User avatar
PS Forum Moderator
Joined: 15 Feb 2021
Last visit: 18 Jun 2025
Posts: 644
Own Kudos:
657
 [1]
Given Kudos: 232
Location: India
WE:Marketing (Internet and New Media)
Products:
Posts: 644
Kudos: 657
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
CoinTheory
Why can't we do: [1000 - (all the numbers that dont contain 3)]? 9*9*9

= 271 --> 271*3

This is why I ended up choosing (c)
This way we miss counting the number of 3's used second or third time in the same digit.

The missing 29 3's are - 33 (1), 133, 233, 333......... 933 (10), 330, 331, 332, 334,..... 339 (9), 303, 313, 323, 343,...... 393 (9)

1+10+9+9 = 29
User avatar
CoinTheory
Joined: 05 Nov 2024
Last visit: 17 Jun 2025
Posts: 4
Given Kudos: 45
Location: United States
GMAT Focus 1: 675 Q86 V85 DI79
GMAT Focus 1: 675 Q86 V85 DI79
Posts: 4
Kudos: 0
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Krunaal
CoinTheory
Why can't we do: [1000 - (all the numbers that dont contain 3)]? 9*9*9

= 271 --> 271*3

This is why I ended up choosing (c)
This way we miss counting the number of 3's used second or third time in the same digit.

The missing 29 3's are - 33 (1), 133, 233, 333......... 933 (10), 330, 331, 332, 334,..... 339 (9), 303, 313, 323, 343,...... 393 (9)

1+10+9+9 = 29

Oh...Ok, I see now. Thank you! :please:
Moderators:
Math Expert
102096 posts
PS Forum Moderator
644 posts