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If a and b are single digits from 0 to 9, inclusive, what is the value 28 Jul 2017, 04:01
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E
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75% (hard)

Question Stats:

58% (02:35) correct 42% (02:39) wrong based on 116 sessions

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If a and b are single digits from 0 to 9, inclusive, what is the value of (a + b)?

(1) The number 25a7b is divisible by 36.
(2) The number a1b is divisible by 4.
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E
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Luckisnoexcuse
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If a and b are single digits from 0 to 9, inclusive, what is the value 28 Jul 2017, 04:42
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Bunuel
If a and b are single digits from 0 to 9, inclusive, what is the value of (a + b)?

(1) The number 25a7b is divisible by 36.
(2) The number a1b is divisible by 4.
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(1)
36*2 = 72
only when b = 2 we can get 7 in the tenth digit
36*702 = 25272
36*712 = 25632 nope
36*722 = 25992 nope
36*692 = 24912 nope
hence a+b = 4

Sufficient

(2) a1b is divisible by 4
b can take 2, 6
a can take 1-9
Not sufficient

A
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If a and b are single digits from 0 to 9, inclusive, what is the value 28 Jul 2017, 08:46
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mynamegoeson
Bunuel
If a and b are single digits from 0 to 9, inclusive, what is the value of (a + b)?

(1) The number 25a7b is divisible by 36.
(2) The number a1b is divisible by 4.

(1)
36*2 = 72
only when b = 2 we can get 7 in the tenth digit
36*702 = 25272
36*712 = 25632 nope
36*722 = 25992 nope
36*692 = 24912 nope
hence a+b = 4

Sufficient

(2) a1b is divisible by 4
b can take 2, 6
a can take 1-9
Not sufficient

A
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luks like E to me....
here are my 2 cents....
if the number is divisible by 36,,it shud be divisible by both 9 and 4
for a number to b divisible by 9,, the sum if digits shud be divisible by 9
for a nummber to b divisible by 4 the last two digits shud be divisible by 4


stat 1: 25776,, a+b = 13
25272 ,,a+b = 4
not suff

stat 2: b can be 2 or 6

both combined two diff ans,,
ans E
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If a and b are single digits from 0 to 9, inclusive, what is the value Updated on: 28 Jul 2017, 09:40
Originally posted by rulingbear on 28 Jul 2017, 09:05.
Last edited by rulingbear on 28 Jul 2017, 09:40, edited 2 times in total.
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Bunuel
If a and b are single digits from 0 to 9, inclusive, what is the value of (a + b)?

(1) The number 25a7b is divisible by 36.
(2) The number a1b is divisible by 4.
Show more

IMO, it helps to start from statement 2 as it's much simpler and may give hints to evaluate statement 1
Statement 2 is insufficient using the divisibility rule by 4 i.e b is either 2 or 6 and a could be any number.

Evaluating statement 1:
From statement 2 we know that b is either 2 or 6 since it's divisible by 25a7b is divisible by 36,

Now combining the divisibility by 4 and 9 to find divisibility by 36, b is inconclusive as 72 and 76 are divisible by 4
Also by extension, a has dual values (2 and 7) that make 2+a+5+7+2 = 18 or 2+a+5+7+6 = 27 divisible by 9

Thus, statement 1 is also insufficient and the answer is E.[/b]
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If a and b are single digits from 0 to 9, inclusive, what is the value 28 Jul 2017, 09:10
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rulingbear
Bunuel
If a and b are single digits from 0 to 9, inclusive, what is the value of (a + b)?

(1) The number 25a7b is divisible by 36.
(2) The number a1b is divisible by 4.

IMO, it helps to start from statement 2 as it's much simpler and may give hints to evaluate statement 1
Statement 2 is insufficient using the divisibility rule by 4 i.e b is either 2 or 6 and a could be any number.

From statement 2 we know that b is either 2 or 6 since it's divisible by 25a7b is divisible by 36, b is clearly 2, i.e last 2 digits cannot be 76.
Now we need to find a, here by approximation the first # of the quotient is 7, i.e 36(8-1) = 288-36= 252
Hence a is clearly 2, as any other number would spill over and would make 25a7b indivisible by 36.
Thus, 1 is sufficient and the answer is A.
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in the number 25776, the last two digits are 76,,, and the number is very much divisible by 36...
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If a and b are single digits from 0 to 9, inclusive, what is the value 28 Jul 2017, 09:15
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mohshu
rulingbear
Bunuel
If a and b are single digits from 0 to 9, inclusive, what is the value of (a + b)?

(1) The number 25a7b is divisible by 36.
(2) The number a1b is divisible by 4.

IMO, it helps to start from statement 2 as it's much simpler and may give hints to evaluate statement 1
Statement 2 is insufficient using the divisibility rule by 4 i.e b is either 2 or 6 and a could be any number.

From statement 2 we know that b is either 2 or 6 since it's divisible by 25a7b is divisible by 36, b is clearly 2, i.e last 2 digits cannot be 76.
Now we need to find a, here by approximation the first # of the quotient is 7, i.e 36(8-1) = 288-36= 252
Hence a is clearly 2, as any other number would spill over and would make 25a7b indivisible by 36.
Thus, 1 is sufficient and the answer is A.


in the number 25776, the last two digits are 76,,, and the number is very much divisible by 36...
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Hi Monshu,

You are clearly right, missed that.
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If a and b are single digits from 0 to 9, inclusive, what is the value 28 Jul 2017, 11:53
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The answer should be E.
Both statements combined you will have two cases:
b=2
and
b=6
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If a and b are single digits from 0 to 9, inclusive, what is the value 29 Jul 2017, 12:45
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mynamegoeson
Bunuel
If a and b are single digits from 0 to 9, inclusive, what is the value of (a + b)?

(1) The number 25a7b is divisible by 36.
(2) The number a1b is divisible by 4.

(1)
36*2 = 72
only when b = 2 we can get 7 in the tenth digit
36*702 = 25272
36*712 = 25632 nope
36*722 = 25992 nope
36*692 = 24912 nope
hence a+b = 4

Sufficient

(2) a1b is divisible by 4
b can take 2, 6
a can take 1-9
Not sufficient

A
Show more

You are forgetting 25776
(1) Divisible by 36 means divisible by 4 and 9.
divisible by 4 means 7b divisible by 4 --> b=2 or 6
divisible by 9 means 2+5+7+a+b divisible by 9 but b can only take 2 or 6
with b=2 --> 16+a divisible by 9 --> a=2
with b=6 --> 20+a divisible by 9 --> a=7
(2) same info

E
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If a and b are single digits from 0 to 9, inclusive, what is the value 03 May 2024, 04:38
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