"Nothing in life is to be feared, it is only to be understood."
- Marie Curie
4.
The difference between a two-digit number and the number obtained by interchanging the digits is 36. What is the difference between the sum and the difference of the digits of the number if the ratio between the digits of the number is 1 : 2 ?
[A].
4
[B].
8
[C].
16
[D].
None of these
Answer: Option C
Explanation:
Since the number is greater than the number obtained on reversing the digits, so the ten's digit is greater than the unit's digit.
Let ten's and unit's digits be 2x and x respectively.
Hi I could not understand this problem. Can anyone explain this more clearly please?
Pavithra said:
(Fri, Sep 24, 2010 12:13:58 PM)
I get the answer as 16.
Diff in digits: (x+y)-(x-y)
=2y
=2(2x)
=4x.
Finding the value of x we get, x=4;
So ans = 4(4) = 16.
Sikha said:
(Thu, Dec 16, 2010 09:00:06 AM)
It can't b (x+y) - (x-y).
Rather it could be (10x +y) - (10y + x).
Sravanthi said:
(Fri, Mar 25, 2011 05:34:23 AM)
Hi I can't understand this problem. Any more explnation please.
Nathi said:
(Wed, May 4, 2011 10:08:30 AM)
At first we should decide the digits of 10's & unit's be X & 2X respectively.
((10 x 2X) + X) - ((10 x X) + 2X) = 36
(20X + X) - (10X + 2X) = 36
21X - 12X = 36
9X = 36
X = 4
The difference between two digits = (2X+X)-(2X-x)
= 3X - X
= 2X
= 2(4)
= 8
Santosh said:
(Sun, Jun 26, 2011 07:33:45 AM)
Why we have to take 2x in units place rather than x ? can any one explain.
Nagendra said:
(Tue, Jun 28, 2011 07:00:29 AM)
Once u find x then try this method to get the answer
21X-12X
21(4)-12(4)
84-48
that means the two number are 84 and 48..
now we have to take the sum of one no and the difference of other no.. according to question sum of digits and difference of digits
that is
48=4+8=12(sum of digits)
84=8-4=4(diff of digits)
now the difference of these two answer
12-4=8
Hence the answer is 8.
Shalini said:
(Sat, Sep 17, 2011 12:15:10 PM)
Why are we choosing 2x?
Mitali said:
(Wed, Oct 19, 2011 11:48:17 AM)
Here we have
The difference between a two-digit number and the number obtained by interchanging the digits is 36
let a,b be 2 numbers
so, a-b=36
ratio between the digits of the number is 1 : 2
let x,y be d digits of a number
x/y=1/2
so, y=2x
now a must be greater than b
here we can see y is greater than x
here
for a => y is ten's digit n x is unit's
for b => x is ten's digit n y is unit's
so (10y+x)-(10x+y)=36
(10*(2x)+x)-(10x + 2x)=36
(21x)-(12x)=36
9x=36
x=4
(y+x)-(y-x)=(x+2x)-(2x-x)=2x=8
Virendra said:
(Tue, Nov 22, 2011 02:07:11 PM)
In question diff is given i.e. 36 and ratio is 1:2
9x = 36 
Required difference = (2x + x) - (2x - x) = 2x = 8.