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Difficulty:
45%
(medium)
Question Stats:
62% (01:58) correct
38%
(01:43)
wrong
based on 158
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If n is an integer from 1 to 9. Is n prime?
(1) 1/n is terminating decimal number
(2) 1/n has at least 3 non zero digits on right of decimal
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Joined: 16 Sep 2014
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Expert reply
Analyzing the question:
Given n can be 1, 2, 3 ... 8, 9.
Is n equal to either 2, 3, 5, or 7?
Statement 1:
For a decimal to terminate, we cannot divide by 3 or any prime number greater than 6.
If 1/n is terminating we can choose n = 1, 2, 4, 5, 8. Out of these n = 2 and n = 5 are prime but the rest aren't, so insufficient.
Statement 2:
We can get a decimal that terminates but has 3 or more digits on the right of the decimal point, or simply a decimal that doesn't terminate.
n = 3, 6, 7, 9 are nonterminating.
n = 8 gives 3 digits. Out of these n = 3 and n = 7 are prime but the rest aren't, insufficient.
Combined:
n = 8 is the only common number in both, sufficient.
Ans: C
_________________
Given n can be 1, 2, 3 ... 8, 9.
Is n equal to either 2, 3, 5, or 7?
Statement 1:
For a decimal to terminate, we cannot divide by 3 or any prime number greater than 6.
If 1/n is terminating we can choose n = 1, 2, 4, 5, 8. Out of these n = 2 and n = 5 are prime but the rest aren't, so insufficient.
Statement 2:
We can get a decimal that terminates but has 3 or more digits on the right of the decimal point, or simply a decimal that doesn't terminate.
n = 3, 6, 7, 9 are nonterminating.
n = 8 gives 3 digits. Out of these n = 3 and n = 7 are prime but the rest aren't, insufficient.
Combined:
n = 8 is the only common number in both, sufficient.
Ans: C
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Quote:
n=1,2,3,4,5,6,7,8,9
(1) 1/n is terminating decimal number insufic
1/n=terminating; n=1,2,4,5,8
(2) 1/n has at least 3 non zero digits on right of decimal insufic
1/n=0.ABC…; 1/8=0.125, n=8≠prime; 1/3=0.333, n=3=prime
(1 and 2) sufic
1/n=terminating; n=1,2,4,5,8 but n=0.ABC (not=0)
1/1=1, 1/2=0.5, 1/4=0.25, 1/5=0.2
n=8…1/8=terminating=0.125
Ans (C)
GMAT 1: 720 Q49 V40
Posts: 939
Updated on: 08 Jan 2020, 01:20
Originally posted by freedom128 on 07 Jan 2020, 06:18.
Last edited by freedom128 on 08 Jan 2020, 01:20, edited 1 time in total.
Last edited by freedom128 on 08 Jan 2020, 01:20, edited 1 time in total.
1) 1/n is terminating decimal number, where n=1,2,4,5,8. Some eligible n are prime (2,5), others (1,4,8) are not.
NOT SUFFICIENT
2) 1/n has at least 3 non zero digits on right of decimal, where n=3,6,7,8,9. Some eligible n are prime (3,7), others (6,8,9) are not.
NOT SUFFICIENT
1)+2) only n=8 satisfies both statements. thus, n=8 is not a prime.
SUFFICIENT
FINAL ANSWER IS (C)
Thanks for lacktutor for correcting me.
Posted from my mobile device
NOT SUFFICIENT
2) 1/n has at least 3 non zero digits on right of decimal, where n=3,6,7,8,9. Some eligible n are prime (3,7), others (6,8,9) are not.
NOT SUFFICIENT
1)+2) only n=8 satisfies both statements. thus, n=8 is not a prime.
SUFFICIENT
FINAL ANSWER IS (C)
Thanks for lacktutor for correcting me.
Posted from my mobile device
If n is an integer from 1 to 9. Is n prime?
(Statement1): \(\frac{1}{n}\) is terminating decimal number.
—> if n=2(prime), then \(\frac{1}{2}\)= 0.5 (YES)
—> if n= 8(not prime), then \(\frac{1}{8}\)= 0.125 (NO)
Insufficient
(Statement2): \(\frac{1}{n}\) has at least 3 non zero digits on right of decimal.
—> if n=3(prime), then \(\frac{1}{3}=0.333\)... (yes)
—> if n= 8(not prime), then \(\frac{1}{8}= 0.125\) (NO)
Insufficient
Taken together 1&2,
—> only one value of n satisfies the both statements—>(n=8).
\(\frac{1}{8} = 0.125\), but n is not prime(always)
Sufficient
The answer is C
Posted from my mobile device
(Statement1): \(\frac{1}{n}\) is terminating decimal number.
—> if n=2(prime), then \(\frac{1}{2}\)= 0.5 (YES)
—> if n= 8(not prime), then \(\frac{1}{8}\)= 0.125 (NO)
Insufficient
(Statement2): \(\frac{1}{n}\) has at least 3 non zero digits on right of decimal.
—> if n=3(prime), then \(\frac{1}{3}=0.333\)... (yes)
—> if n= 8(not prime), then \(\frac{1}{8}= 0.125\) (NO)
Insufficient
Taken together 1&2,
—> only one value of n satisfies the both statements—>(n=8).
\(\frac{1}{8} = 0.125\), but n is not prime(always)
Sufficient
The answer is C
Posted from my mobile device
Archit3110
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GMAT Focus 1: 545 Q79 V79 DI73
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GMAT Focus 2: 645 Q83 V82 DI81
Posts: 8,816
Updated on: 11 Jan 2020, 00:21
Originally posted by Archit3110 on 07 Jan 2020, 17:58.
Last edited by Archit3110 on 11 Jan 2020, 00:21, edited 1 time in total.
Last edited by Archit3110 on 11 Jan 2020, 00:21, edited 1 time in total.
#1
1/n is terminating decimal number
Yes for 2,5 and 4 insufficient
#2
1/n has at least 3 non zero digits on right of decimal
Only possible no is 7 or 8
insufficient
from 1 &2
no has to be 8
IMO C
If n is an integer from 1 to 9. Is n prime?
(1) 1/n is terminating decimal number
(2) 1/n has at least 3 non zero digits on right of decimal
Posted from my mobile device
1/n is terminating decimal number
Yes for 2,5 and 4 insufficient
#2
1/n has at least 3 non zero digits on right of decimal
Only possible no is 7 or 8
insufficient
from 1 &2
no has to be 8
IMO C
If n is an integer from 1 to 9. Is n prime?
(1) 1/n is terminating decimal number
(2) 1/n has at least 3 non zero digits on right of decimal
Posted from my mobile device
QuantMadeEasy
Joined: 27 Feb 2014
Last visit: 01 Mar 2026
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Location: India
Concentration: General Management, International Business
GPA: 3.97
WE:Engineering (Education)
Posts: 502
(1) 1/n is terminating decimal number
To get a terminating decimal,n has be either 2 or 5. Sufficient
(2) 1/n has at least 3 non zero digits on right of decimal
possible values of n can be = 3, 6, 7,8. Insufficient
A is correct.
To get a terminating decimal,n has be either 2 or 5. Sufficient
(2) 1/n has at least 3 non zero digits on right of decimal
possible values of n can be = 3, 6, 7,8. Insufficient
A is correct.
madgmat2019
Joined: 01 Mar 2019
Last visit: 17 Sep 2021
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Location: India
Concentration: Strategy, Social Entrepreneurship
GMAT 1: 580 Q48 V21
GPA: 4
Products:
GMAT 1: 580 Q48 V21
Posts: 584
(1) 1/n is terminating decimal number......1/2,1/4,1/5/1/8... Satisfies... but all are not prime...INSUFFICIENT
(2) 1/n has at least 3 non zero digits on right of decimal......1/3,1/7,1/9,1/6.....but all are not prime...INSUFFICIENT
OA:E
(2) 1/n has at least 3 non zero digits on right of decimal......1/3,1/7,1/9,1/6.....but all are not prime...INSUFFICIENT
OA:E
chondro48
Hi, chondro48
If you combine statement 1&2 together, only n=8 satisfies the both statements, not n=3.
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