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 5 of 6.
Sudha said:
1 decade ago
Why are you taking the 10 digit number. Why not take other digits?
Nani said:
1 decade ago
Why we are adding 10x+y why n't 10xy?
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.
Prince said:
1 decade ago
Thanks you anshu mam & aravind sir.
Navya nyeni said:
1 decade ago
Actually we are assuming here as x and y as we need to find d value given you can take any variables to caluculate thats not restricted.
Swati said:
1 decade ago
Why in solution its written tens digit be x and unit digit be y? can any one explain me. ?
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)
Aparna said:
1 decade ago
Thank you Aravind.
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.
Meghna jain said:
1 decade ago
Please explain in simple form.
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