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If a and b are single digits from 0 to 9, inclusive, what is the value
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28 Jul 2017, 03:01
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Re: If a and b are single digits from 0 to 9, inclusive, what is the value
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28 Jul 2017, 03:42
Bunuel wrote: 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 19 Not sufficient A
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Re: If a and b are single digits from 0 to 9, inclusive, what is the value
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28 Jul 2017, 07:46
mynamegoeson wrote: Bunuel wrote: 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 19 Not sufficient A 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
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Updated on: 28 Jul 2017, 08:40
Bunuel wrote: 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. 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]
Originally posted by rulingbear on 28 Jul 2017, 08:05.
Last edited by rulingbear on 28 Jul 2017, 08:40, edited 2 times in total.



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Re: If a and b are single digits from 0 to 9, inclusive, what is the value
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28 Jul 2017, 08:10
rulingbear wrote: Bunuel wrote: 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(81) = 28836= 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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Re: If a and b are single digits from 0 to 9, inclusive, what is the value
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28 Jul 2017, 08:15
mohshu wrote: rulingbear wrote: Bunuel wrote: 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(81) = 28836= 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... Hi Monshu, You are clearly right, missed that.



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Re: If a and b are single digits from 0 to 9, inclusive, what is the value
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28 Jul 2017, 10:53
The answer should be E. Both statements combined you will have two cases: b=2 and b=6



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Re: If a and b are single digits from 0 to 9, inclusive, what is the value
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29 Jul 2017, 11:45
mynamegoeson wrote: Bunuel wrote: 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 19 Not sufficient A 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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Re: If a and b are single digits from 0 to 9, inclusive, what is the value
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20 Sep 2018, 04:14
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