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Problem Solving

by RiyaR » Mon Aug 04, 2014 9:02 pm
If x,y and z are single digit integers and 100(x)+ 1,000(y)+10(z)=N. What is the unit's digit of the number N?
A) 0
B) 1
C) x
D) y
E) z
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by [email protected] » Mon Aug 04, 2014 9:13 pm
Hi RiyaR,

This is a "concept" question, meaning that you need to think about what the information "really means" to answer it. It can also be solved by TESTing VALUES.

Let's TEST:

X = 2
Y = 3
Z = 4

100(2) + 1000(3) + 10(4) = N
200 + 3000 + 40 = N
3240 = N

The question asks for the "unit's digit" (aka the "one's digit"). The unit's digit is 0

Final Answer: A

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by GMATinsight » Tue Aug 05, 2014 10:31 am
RiyaR wrote:If x,y and z are single digit integers and 100(x)+ 1,000(y)+10(z)=N. What is the unit's digit of the number N?
A) 0
B) 1
C) x
D) y
E) z
A 4 Digit Number ABCD is defined by

1000A + 100B + 10C + D where D is the Unit digit

Here 100(x)+ 1,000(y)+10(z)=N

Unit digit is not there therefore it is bound to be zero
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by GMATinsight » Tue Aug 05, 2014 10:32 am
RiyaR wrote:If x,y and z are single digit integers and 100(x)+ 1,000(y)+10(z)=N. What is the unit's digit of the number N?
A) 0
B) 1
C) x
D) y
E) z
A 4 Digit Number ABCD is defined by

1000A + 100B + 10C + D where D is the Unit digit

Here 100(x)+ 1,000(y)+10(z)=N

Unit digit is not there therefore it is bound to be zero
"GMATinsight"Bhoopendra Singh & Sushma Jha
Most Comprehensive and Affordable Video Course 2000+ CONCEPT Videos and Video Solutions
Whatsapp/Mobile: +91-9999687183 l [email protected]
Contact for One-on-One FREE ONLINE DEMO Class Call/e-mail
Most Efficient and affordable One-On-One Private tutoring fee - US$40-50 per hour
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by GMATinsight » Tue Aug 05, 2014 10:34 am
RiyaR wrote:If x,y and z are single digit integers and 100(x)+ 1,000(y)+10(z)=N. What is the unit's digit of the number N?
A) 0
B) 1
C) x
D) y
E) z
ALTERNATE

Here 100(x)+ 1,000(y)+10(z)=N

Unit Digit of 100x = 0
Unit Digit of 1000Y = 0
Unit Digit of 10z = 0

Therefore Unit Digit of N = 0
"GMATinsight"Bhoopendra Singh & Sushma Jha
Most Comprehensive and Affordable Video Course 2000+ CONCEPT Videos and Video Solutions
Whatsapp/Mobile: +91-9999687183 l [email protected]
Contact for One-on-One FREE ONLINE DEMO Class Call/e-mail
Most Efficient and affordable One-On-One Private tutoring fee - US$40-50 per hour
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