Aptitude - Numbers - Discussion

Discussion Forum : Numbers - General Questions (Q.No. 46)
46.
In dividing a number by 585, a student employed the method of short division. He divided the number successively by 5, 9 and 13 (factors 585) and got the remainders 4, 8, 12 respectively. If he had divided the number by 585, the remainder would have been
24
144
292
584
Answer: Option
Explanation:
 5 | x                z = 13 x 1 + 12  = 25
 --------------
 9 | y - 4            y = 9 x z + 8  = 9 x 25 + 8  = 233
 --------------
 13| z - 8            x = 5 x y + 4  = 5 x 233 + 4  = 1169
 --------------
   | 1 -12
  
  585) 1169 (1
       585
       ---
       584
       ---
       
  Therefore, on dividing the number by 585, remainder = 584.     
Discussion:
39 comments Page 4 of 4.

Suneetha said:   1 decade ago
@Dharamveer.

Divided the number successively by 5, 9 and 13 (factors 585) and got the remainders 4, 8, 12 respectively.

Dividers are 5, 9, 13.

Remainders are 4, 8, 12.

k = divider-remainder = 5-4 = 9-8 = 13-12 = 1.

Dharamveer said:   1 decade ago
@Sudhir.

How can we say that the value of k=1.

Sudhir said:   1 decade ago
On dividing a number by a,b,c if we get a-k, b-k nd c-k as remainder respectively then that number will be N*LCM of[a,b,c]-k.
therefore:
=N*[lcm of 5,9,13]-1
=N*[585]-1
=N*584
=584 here N=1

Chandru said:   1 decade ago
Thanks Ms. Arthy.

FEuR!aN [- _ -] said:   1 decade ago
Thanks manideep.
(1)

Neelu said:   1 decade ago
Thanku arti. For helping to understand this problem in easy way.
(1)

Nikhil said:   1 decade ago
thnx arti
(1)

Manideep said:   1 decade ago
@ Arti

Let the number be x.

Now given x=5a+4, a=9b+8, b=13c+12...

By reverse substitution you get

a = 9(13c + 12) + 8 = (13*9)c + 116

x = 5[(13 * 9)c + 116] + 4 = 585c + 584

So this when divided by 585 you get 584 as reminder.

Thank you :)
(3)

Arti said:   1 decade ago
Hi, can any one please explain it I'm not able to understand how's these equation are working. Sorry but Im not able to understand. : (.
(1)


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