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 1 of 6.
Shams said:
1 decade ago
Hi,
There is not taking 10 digit number. that is the 10th place of number we are finding. see
There are 2 two digit is let x and y,
So the number will be 10x+y (x is at tenth position & y is at unit position)
Because for example number 85.
x=8 and y=5.
So, 10x+y = ( 10 * 8 + 5 = 85 ).
Not do the number (xy = 8*5 = 40) or (10xy = 10*8*5 =400 ).
Now for answer proceed further according to question.
I think its help to you.
There is not taking 10 digit number. that is the 10th place of number we are finding. see
There are 2 two digit is let x and y,
So the number will be 10x+y (x is at tenth position & y is at unit position)
Because for example number 85.
x=8 and y=5.
So, 10x+y = ( 10 * 8 + 5 = 85 ).
Not do the number (xy = 8*5 = 40) or (10xy = 10*8*5 =400 ).
Now for answer proceed further according to question.
I think its help to you.
(1)
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)
Nikhilesh Israni said:
1 decade ago
Here we are writing the place value of each digit.
Suppose we have a number 7245, then the place value of 5 is 5*1=5 and the place value of 4 is 4*10=40. Similarly 2*100=200 and 7*1000=7000.
Hence if the number is 'xy' then y's place value is y*1=y and x's is x*10=10x. The same rule applies when we interchange the numbers.
Suppose we have a number 7245, then the place value of 5 is 5*1=5 and the place value of 4 is 4*10=40. Similarly 2*100=200 and 7*1000=7000.
Hence if the number is 'xy' then y's place value is y*1=y and x's is x*10=10x. The same rule applies when we interchange the numbers.
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)
Megha said:
1 year ago
@All.
Now for example;
Take the number to be 54(example), then in units place we have 4 and in tens place we have 5
Separately,
x = 5
y = 4
For xth place 10*5=50
For yth place. +4
= 54
Hence 10*x + y ---->(1)
After interchanging in xth place we have y so,
10*y + x -----> (2)
So that's why we have 10.
Now for example;
Take the number to be 54(example), then in units place we have 4 and in tens place we have 5
Separately,
x = 5
y = 4
For xth place 10*5=50
For yth place. +4
= 54
Hence 10*x + y ---->(1)
After interchanging in xth place we have y so,
10*y + x -----> (2)
So that's why we have 10.
(5)
Aravind said:
1 decade ago
Actually here we taken as 2 digit number.
i.e, 10*digit1 + digit2 = two-digit number.
inter changing.i.e, digit2*10 + digit1 = two-digit number.
difference b/w two-digit number & after inter changing that two-digit number is equal to 36.
say digit1=x,digit2=y,
then, (10x+y)-(10y+x)=36,
We get x-y=4.
i.e, 10*digit1 + digit2 = two-digit number.
inter changing.i.e, digit2*10 + digit1 = two-digit number.
difference b/w two-digit number & after inter changing that two-digit number is equal to 36.
say digit1=x,digit2=y,
then, (10x+y)-(10y+x)=36,
We get x-y=4.
Anshu 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
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
(1)
Abhijit Kale said:
10 years ago
Guys I agree to your explanation but I found a No. 73. If we reverse it we'll get a no 37. And difference between these two nos is 36.
And difference between digits of this no is 3. All these things matches the criteria of this question except my answer. Please rectify me if I am wrong.
And difference between digits of this no is 3. All these things matches the criteria of this question except my answer. Please rectify me if I am wrong.
Tanya said:
8 years ago
(10x + y) - (10y + x) = 36.
Will someone explain to me why we equalize it with 36?
Is it because it is stated, "the number obtained by interchanging the positions of its digits is 36".
Then please explain me the question " What is the difference between the two digits of that number"?
Will someone explain to me why we equalize it with 36?
Is it because it is stated, "the number obtained by interchanging the positions of its digits is 36".
Then please explain me the question " What is the difference between the two digits of that number"?
(1)
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.
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