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# What is the units digit of (493) (915) (381) (756) (29)

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Intern
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What is the units digit of (493) (915) (381) (756) (29) [#permalink]  14 May 2013, 07:41
00:00

Difficulty:

5% (low)

Question Stats:

88% (01:14) correct 12% (00:39) wrong based on 82 sessions
What is the units digit of (493) (915) (381) (756) (29)

A. 0
B. 1
C. 4
D. 5
E. 6
[Reveal] Spoiler: OA
Intern
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Re: What is the units digit of (493) (915) (381) (756) (29) [#permalink]  16 May 2013, 06:51
3
KUDOS
Hi clciotola..

(493)(915)(381)(756)(29)

For example .....

lets take $$13 * 15$$ ...

we get 195.... You can see that If you multiply any odd number with 5 the units digit of the result will be 5.Why?
The last digit oof the odd number will be one of 1, 3, 5,7,9. If you multiply any of these digits with 5 you will get 5 as the units digit in the result.

Now lets take another example with an even number. take 12 * 15.

It is 180. Now 12 can be written as 2*6.Multiply 2 with 15 you will get 30.Now no matter what you multiply 30 with you will always get 0 in the units place.

So any even number when multiplied by 5 will give a result with 0 in the units place.

Lets get back to the question. If we muliptly 493 ,381 and 29 we will get an odd number

Let this result be x. so x is odd

If x is multiplied with an even number the result will be even right??(odd*even = even)

lets multiply x with 756. The result will be even.

Let this result be Y.

Now Y is an even number and you have to multiply it with 15. 15 has 5 in it.So the last digit in the result will be 0.

Hope this helps
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Re: Number proprieties [#permalink]  14 May 2013, 07:48
1
KUDOS
Just multiply the digits in the units place for each term and you will get the answer. It should be 0. you got a 5 as a unit digit and an even number term. so the multiplication of this will definitely yield a 0. Answer has to be 0.
I also tried it using the calculator and the answer is 0.

IMO A.
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Re: Number proprieties [#permalink]  14 May 2013, 07:45
clciotola wrote:
what is the units digit of (493) (915) (381) (756) (29)

a 0
b 1
c 4
d 5
e 6

any help to solve this in a fast way?

thank you!

I think the answer is A

If you observe the numbers we have a 5 and a two in the factors. If you multiply we will always get a zero in the units place no matter what the other numbers are.

Is this a official question?
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Re: Number proprieties [#permalink]  14 May 2013, 07:50
SrinathVangala wrote:
clciotola wrote:
what is the units digit of (493) (915) (381) (756) (29)

a 0
b 1
c 4
d 5
e 6

any help to solve this in a fast way?

thank you!

I think the answer is A

If you observe the numbers we have a 5 and a two in the factors. If you multiply we will always get a zero in the units place no matter what the other numbers are.

Is this a official question?

the answers is E it's an official question!
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Re: Number proprieties [#permalink]  14 May 2013, 07:52
Can you please post the source and if possible the official explanation?
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Re: Number proprieties [#permalink]  14 May 2013, 07:53
coolpintu wrote:
Can you please post the source and if possible the official explanation?

i don't have, i will try to ask to my teacher
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Re: What is the units digit of (493) (915) (381) (756) (29) [#permalink]  14 May 2013, 15:07
It is definitely A ... 0 .... U VE EVEN NUMBERS AND NUMBERS ENDING WITH 5 ... ... CHECK WITH A CALCULATOR
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Re: Number proprieties [#permalink]  14 May 2013, 17:01
SrinathVangala wrote:
clciotola wrote:
what is the units digit of (493) (915) (381) (756) (29)

a 0
b 1
c 4
d 5
e 6

any help to solve this in a fast way?

thank you!

I think the answer is A

If you observe the numbers we have a 5 and a two in the factors. If you multiply we will always get a zero in the units place no matter what the other numbers are.

Is this a official question?

I answered A, but itsays E. I checked with a calculator, it ends with 0.

Intern
Joined: 12 Apr 2013
Posts: 16
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Re: Number proprieties [#permalink]  16 May 2013, 05:00
BengalScientist wrote:
SrinathVangala wrote:
clciotola wrote:
what is the units digit of (493) (915) (381) (756) (29)

a 0
b 1
c 4
d 5
e 6

any help to solve this in a fast way?

thank you!

I think the answer is A

If you observe the numbers we have a 5 and a two in the factors. If you multiply we will always get a zero in the units place no matter what the other numbers are.

Is this a official question?

I answered A, but itsays E. I checked with a calculator, it ends with 0.

Guys the official answer is the A!
but i still have problem to understand can you plese post the calculation step by step? thank you in advance
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Re: What is the units digit of (493) (915) (381) (756) (29) [#permalink]  16 May 2013, 07:05
SrinathVangala wrote:
Hi clciotola..

(493)(915)(381)(756)(29)

For example .....

lets take $$13 * 15$$ ...

we get 195.... You can see that If you multiply any odd number with 5 the units digit of the result will be 5.Why?
The last digit oof the odd number will be one of 1, 3, 5,7,9. If you multiply any of these digits with 5 you will get 5 as the units digit in the result.

Now lets take another example with an even number. take 12 * 15.

It is 180. Now 12 can be written as 2*6.Multiply 2 with 15 you will get 30.Now no matter what you multiply 30 with you will always get 0 in the units place.

So any even number when multiplied by 5 will give a result with 0 in the units place.

Lets get back to the question. If we muliptly 493 ,381 and 29 we will get an odd number

Let this result be x. so x is odd

If x is multiplied with an even number the result will be even right??(odd*even = even)

lets multiply x with 756. The result will be even.

Let this result be Y.

Now Y is an even number and you have to multiply it with 15. 15 has 5 in it.So the last digit in the result will be 0.

Hope this helps

thank you very nice!! just the stal question when you say "Lets get back to the question. If we muliptly 493 ,381 and 29 we will get an odd number" multiply by what??
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Re: What is the units digit of (493) (915) (381) (756) (29) [#permalink]  16 May 2013, 07:07
493*381*29 = odd number
_________________

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Re: What is the units digit of (493) (915) (381) (756) (29) [#permalink]  23 May 2013, 13:04
SrinathVangala wrote:
Hi clciotola..

(493)(915)(381)(756)(29)

For example .....

lets take $$13 * 15$$ ...

we get 195.... You can see that If you multiply any odd number with 5 the units digit of the result will be 5.Why?
The last digit oof the odd number will be one of 1, 3, 5,7,9. If you multiply any of these digits with 5 you will get 5 as the units digit in the result.

Now lets take another example with an even number. take 12 * 15.

It is 180. Now 12 can be written as 2*6.Multiply 2 with 15 you will get 30.Now no matter what you multiply 30 with you will always get 0 in the units place.

So any even number when multiplied by 5 will give a result with 0 in the units place.

Lets get back to the question. If we muliptly 493 ,381 and 29 we will get an odd number

Let this result be x. so x is odd

If x is multiplied with an even number the result will be even right??(odd*even = even)

lets multiply x with 756. The result will be even.

Let this result be Y.

Now Y is an even number and you have to multiply it with 15. 15 has 5 in it.So the last digit in the result will be 0.

Hope this helps

(493) (915) (381) (756) (29)

Take 915 * 756, one has 6 and the other has 5 in units place. it will yield 0 (when multiplied 6*5 =30) at the end. Any number when multiplied with 10, 20, 30...100 would yield 0 in units place that is the case for this example.
Re: What is the units digit of (493) (915) (381) (756) (29)   [#permalink] 23 May 2013, 13:04
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# What is the units digit of (493) (915) (381) (756) (29)

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