Aptitude - Problems on Numbers - Discussion
Discussion Forum : Problems on Numbers - General Questions (Q.No. 3)
3.
The difference between a two-digit number and the number obtained by interchanging the positions of its digits is 36. What is the difference between the two digits of that number?
Answer: Option
Explanation:
Let the ten's digit be x and unit's digit be y.
Then, (10x + y) - (10y + x) = 36
9(x - y) = 36
x - y = 4.
Video Explanation: https://youtu.be/7QOJjAmGVx0
Discussion:
59 comments Page 3 of 6.
Bhavya said:
1 decade ago
@Sudha.
They take 10 number because of it is in ten's place. So they take 10 number :).
They take 10 number because of it is in ten's place. So they take 10 number :).
Sri said:
1 decade ago
Let x and y be two digits of the Numbers.
Such that x is in tens position and y is at the ones place.
So xy is the number,
xy = 10(x) + y(1) ----------> (1).
On interchanging the digits we get,
yx = y(10) + x(1) ----------> (2).
(10x + y) - (10y + x)= 36.
10x + y - 10y - x = 36.
9x - 9y = 36.
x - y = 4.
This explanation is super @Anshu.
Such that x is in tens position and y is at the ones place.
So xy is the number,
xy = 10(x) + y(1) ----------> (1).
On interchanging the digits we get,
yx = y(10) + x(1) ----------> (2).
(10x + y) - (10y + x)= 36.
10x + y - 10y - x = 36.
9x - 9y = 36.
x - y = 4.
This explanation is super @Anshu.
(5)
Sohan said:
1 decade ago
Hello guys,
The explanation that all of them have done is extremely excellent. But I have a doubt Can anyone explain me as, if they ask us to find the numbers in same questions. Then what is procedure to be followed.
Thank you.
The explanation that all of them have done is extremely excellent. But I have a doubt Can anyone explain me as, if they ask us to find the numbers in same questions. Then what is procedure to be followed.
Thank you.
Pukkaprotagonist@gmail.com said:
1 decade ago
Tell me if we have used any formula there or its just common sense :D.
Mohankumar said:
1 decade ago
To overcome like this problems, you have to know very basic thing i.e how do we expand a number??
eg, 345=3*100+4*10+5*1 right?
So now assume digits as xy then u expand it x*10+y*1=xy;
Similar way interchange digits xy-->yx isn't it?
So expand yx=y*10+x*1;
Now you xy-yx=36;(put expanded form in this);
Simplify it..
eg, 345=3*100+4*10+5*1 right?
So now assume digits as xy then u expand it x*10+y*1=xy;
Similar way interchange digits xy-->yx isn't it?
So expand yx=y*10+x*1;
Now you xy-yx=36;(put expanded form in this);
Simplify it..
(2)
Sandt said:
1 decade ago
Some time they take 10 digit no x and some time 10x. Why anybody explain me?
Aparna devi said:
1 decade ago
Why have they taken 10 only?
Nishant said:
1 decade ago
Is that method of considering 10 for the units place should be applied for all the problems?
Arun said:
1 decade ago
I need more explanations for this problem.
Abdul kalam said:
1 decade ago
9x - 9y = 36.
x - y = 4.
How did you get 9?
x - y = 4.
How did you get 9?
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