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Heretic
Joined: 04 May 2006
Posts: 7
Location: Pune
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 Posted: Wed May 17, 2006 12:15 pm Post subject: How to find last two digits of a product ? |
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Find the last two digits in the multiplication of ...
1. 122 x 123 x 125 x 127 x 129
A) 20
B) 50
C) 30
D) 40
2. 15 x 37 x 63 x 51 x 97 x 17
A) 35
B) 40
C) 55
D) 85
Please explain, if possible, the thought process in such type of questions. |
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sahil_avi
Joined: 20 May 2006
Posts: 1
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| Posted: Sat May 20, 2006 10:11 pm Post subject: |
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| its simple, u don't need to multiply all didgits of number, just multiply 2 no. last two digits n find only last two digits, then mltiply last two digits with another given no. go on to find the answer. |
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mj_sadiq
Joined: 24 May 2006
Posts: 1
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| Posted: Wed May 24, 2006 6:35 am Post subject: Hii |
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always check for the numbers that have given ...
1 of the number ends with "5"....
so whenever u multiply with "5" it ends with either 5 or 0..
so its very simple.. the answer which ends with 0 is the answer.
Hope I have cleared your doubts..
Cheers,
Sadiq |
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Dumbo in CAT
Been around a while
Joined: 01 May 2006
Posts: 28
Location: Trivandrum
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| Posted: Sun Jul 02, 2006 10:45 am Post subject: |
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Sorry Sidiq...Ur answer is wrong...it actually ends with 35..
and if a no. is multiplied by 5, the last no will be 5 or 0. But all the answers hav 5 or 0..so it cant be explained like that... |
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CZ@@@H@@@R
Serious about CAT
Joined: 14 Jan 2006
Posts: 64
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| Posted: Thu Jul 06, 2006 2:55 pm Post subject: Re: How to find last two digits of a product ? |
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| Quote: | Find the last two digits in the multiplication of ...
1. 122 x 123 x 125 x 127 x 129
A) 20
B) 50
C) 30
D) 40
2. 15 x 37 x 63 x 51 x 97 x 17
A) 35
B) 40
C) 55
D) 85
Please explain, if possible, the thought process in such type of questions. |
General method is to find mod (100)
1. 125 multiplied by an even no. gives last 2 digits as 00 or 50, Hence (B) |
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apgo2000
Joined: 13 Jul 2006
Posts: 15
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| Posted: Fri Jul 14, 2006 8:15 pm Post subject: |
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hi
wat do u mean by mod(100)??
plz explain.
and plz try the second question too.
regards,
anshu |
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