Greatest Number

harsh.champ wrote:Find the greatest number which divides 285 and 1249,leaving remainders 9 and 7 respectively.

(A)138
(B)128
(C)118
(D)148
(E)158

Correct answer (A) i just mentally divided 285 by 138, remainder of which is 7 and selected this answer. Did the same with 1249. Wish someone would show a better approach.

Hi,
I used following approach:
Subtracting 9 from 285 gives us 276, which must be a multiple of one of the correct answer choices. Clearly, we can see that the answer must be 138. To recheck, subtract 7 from 1249, which gives us 1242. 1242 = 138 * 9
Harsh, can you please post the source for this question. I thought that the answer choices in GMAT are ALWAYS in ascending order. The arrangement of these answer choices dosen't look right.

komal wrote:

harsh.champ wrote:Find the greatest number which divides 285 and 1249,leaving remainders 9 and 7 respectively.

(A)138
(B)128
(C)118
(D)148
(E)158

Correct answer (A) i just mentally divided 285 by 138, remainder of which is 7 and selected this answer. Did the same with 1249. Wish someone would show a better approach.

harsh.champ wrote:Find the greatest number which divides 285 and 1249,leaving remainders 9 and 7 respectively.

(A)138
(B)128
(C)118
(D)148
(E)158

285-9 = 276 which is clearly 23x3x2
1249 -7=1242 = 2x3x3x3x23
HCF = 2x3x23 =138 Just use the simple concept of HCF Ans A

amittilak wrote:Hi,
I used following approach:
Subtracting 9 from 285 gives us 276, which must be a multiple of one of the correct answer choices. Clearly, we can see that the answer must be 138. To recheck, subtract 7 from 1249, which gives us 1242. 1242 = 138 * 9
Harsh, can you please post the source for this question. I thought that the answer choices in GMAT are ALWAYS in ascending order. The arrangement of these answer choices dosen't look right.

komal wrote:

harsh.champ wrote:Find the greatest number which divides 285 and 1249,leaving remainders 9 and 7 respectively.

(A)138
(B)128
(C)118
(D)148
(E)158

Correct answer (A) i just mentally divided 285 by 138, remainder of which is 7 and selected this answer. Did the same with 1249. Wish someone would show a better approach.

Hey amittilak,
That was a good approach adopted by you.As for the answer choices,I had purposely set them in random order just to make the question more challenging.Well,Can a question in GMAT never come in random order(instead of ascending or descending)?Just asking.Anyways from next time,I will post the ques. in the normal order only.Thanks for informing!!