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If a and b are positive integers, what is the units digit of [#permalink]
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Updated on: 17 Jun 2014, 12:32
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If a and b are positive integers, what is the units digit of b ? (1) b is 25% greater than a. (2) If b is decreased by 50%, the result is not an integer.
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Originally posted by honchos on 17 Jun 2014, 12:28.
Last edited by Bunuel on 17 Jun 2014, 12:32, edited 1 time in total.
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Re: If a and b are positive integers, what is the units digit of [#permalink]
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17 Jun 2014, 12:36
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Re: If a and b are positive integers, what is the units digit of [#permalink]
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03 Aug 2015, 09:55
Hi Bunuel,
I think it should be A as the question stem states that a & b are positive integers, ruling out the possibility of b being 0.
Your comments please



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If a and b are positive integers, what is the units digit of [#permalink]
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03 Aug 2015, 10:14
kakshay108@gmail.com wrote: Hi Bunuel,
I think it should be A as the question stem states that a & b are positive integers, ruling out the possibility of b being 0.
Your comments please Not really. Positive integers can also include numbers such as 10, 20, 35 , 77 or even 1000. Having a ,b POSITIVE INTEGERS only means that the selected integers are >0 NOT that their unit's digit is 0 (this may or may not be true as shown below). Per statement 1, b = 1.25 a This statement can not be sufficient as you do not know about a. Take 2 cases: a= 4, b = 5, units digit = 5 a =16, b = 20, unit's digit = 0 . Hence you get 2 different answers. Thus this statement is not sufficient.



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Re: If a and b are positive integers, what is the units digit of [#permalink]
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17 Sep 2015, 20:50
kakshay108@gmail.com wrote: Hi Bunuel,
I think it should be A as the question stem states that a & b are positive integers, ruling out the possibility of b being 0.
Your comments please Bunuel has mentioned that "the units digit of b could be 0"...he is not saying b is 0..Hope this clears your doubt.



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Re: If a and b are positive integers, what is the units digit of [#permalink]
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14 Apr 2016, 18:24
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honchos wrote: If a and b are positive integers, what is the units digit of b ? (1) b is 25% greater than a. (2) If b is decreased by 50%, the result is not an integer. 1. b=5a/4 so a must be a multiple of 4, and b a multiple of 5. a=4, b=5. a=8, b=10, 2 options, not sufficient. 2. b/2 = noninteger. so b is odd. 1+2. b is odd, and b is a multiple of 5. 5, 15, 25, 35, 45, etc. so always b has units digit 5.



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Re: If a and b are positive integers, what is the units digit of [#permalink]
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05 Oct 2017, 22:35
honchos wrote: If a and b are positive integers, what is the units digit of b ? (1) b is 25% greater than a. (2) If b is decreased by 50%, the result is not an integer. Given : positive integers a and b DS: units digit of b? Statement 1 : b = 1.25 a = (5/4)a So a is multiple of 4 and b is a multiple of 5 a= 4, b =5 a=8, b=10 a=12, b=15 a=16, b= 20 So, unit's digit of b is either 0 or 5 NOT SUFFICIENT Statement 2 : Lets say the resultant value is c. So c = 0.5b and c is not an integer. So, c must be an odd integer. Unit's digit can be 1,3,5,7,9 NOT SUFFICIENT Combined : Unit's digit = 5 SUFFICIENT
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Re: If a and b are positive integers, what is the units digit of [#permalink]
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09 Jan 2018, 08:54
shashankism wrote: honchos wrote: If a and b are positive integers, what is the units digit of b ? (1) b is 25% greater than a. (2) If b is decreased by 50%, the result is not an integer. Given : positive integers a and b DS: units digit of b? Statement 1 : b = 1.25 a = (5/4)a So a is multiple of 4 and b is a multiple of 5 a= 4, b =5 a=8, b=10 a=12, b=15 a=16, b= 20 So, unit's digit of b is either 0 or 5 NOT SUFFICIENT Statement 2 : Lets say the resultant value is c. So c = 0.5b and c is not an integer. So, c must be an odd integer. Unit's digit can be 1,3,5,7,9 NOT SUFFICIENT Combined : Unit's digit = 5 SUFFICIENTDo you mean that "b" must be an odd integer? Typo.




Re: If a and b are positive integers, what is the units digit of
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