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Which of the following is the units digit for the sum of all of the di
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18 May 2023, 10:47
18 May 2023, 10:47
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Question Stats:
76% (00:54) correct
23% (01:32) wrong based on 13 sessions
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Which of the following is the units digit for the sum of all of the distinct prime integers less than 20?
A. 4
B. 5
C. 6
D. 7
E. 8
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A. 4
B. 5
C. 6
D. 7
E. 8
Post A Detailed Correct Solution For The Above Questions And Get A Kudos.
Question From Our Project: Free GRE Prep Club Tests in Exchange for 20 Kudos
\(\Longrightarrow\) Cracking the GRE Premium
\(\Longrightarrow\) GRE Math Essentials - A most comprehensive handout!!
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Joined: 20 Feb 2017
Posts: 2506
Given Kudos: 1055
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Re: Which of the following is the units digit for the sum of all of the di
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20 May 2023, 11:17
20 May 2023, 11:17
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Expert Reply
To find the sum of all the distinct prime numbers less than 20, we can list out the prime numbers and add them together:
2 + 3 + 5 + 7 + 11 + 13 + 17 + 19 = 77
The units digit of 77 is 7.
Therefore, the correct answer is D. 7.
2 + 3 + 5 + 7 + 11 + 13 + 17 + 19 = 77
The units digit of 77 is 7.
Therefore, the correct answer is D. 7.
Re: Which of the following is the units digit for the sum of all of the di
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11 Apr 2024, 13:18
11 Apr 2024, 13:18
1
The prime numbers from 1 to 20 are
2,3,5,7,11,13,17,19
To save time we can notice that three pairs of primes - 3+7, 13+17, 11+19 will have zeros when added as their last digit.
So we only need to add 2 to 5 and get 7.
2,3,5,7,11,13,17,19
To save time we can notice that three pairs of primes - 3+7, 13+17, 11+19 will have zeros when added as their last digit.
So we only need to add 2 to 5 and get 7.
