Aptitude - Problems on Numbers - Discussion
Discussion Forum : Problems on Numbers - General Questions (Q.No. 4)
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 ?
Answer: Option
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.
Then, (10 x 2x + x) - (10x + 2x) = 36
9x = 36
x = 4.
Required difference = (2x + x) - (2x - x) = 2x = 8.
Discussion:
45 comments Page 3 of 5.
S.prema said:
1 decade ago
Thanks for the explanation.
Jonsihay said:
10 years ago
The Problem should be re-stated specially on the aspect of the ratio.
It should "NOT JUST BE" 'if the ratio between the digits of the number is 1:2. But it should be restated as 'if the ratio between the unit's and ten's digits of the number is 1:2.
Then if that's ok, I think reliably be solvable!
It should "NOT JUST BE" 'if the ratio between the digits of the number is 1:2. But it should be restated as 'if the ratio between the unit's and ten's digits of the number is 1:2.
Then if that's ok, I think reliably be solvable!
(1)
Rajesh jangid said:
10 years ago
Hi can anyone explain when to take 2x and x and when 10x+y-10y-x?
Aditrya tiwari said:
9 years ago
Consider no is 10x + y.
Then according to first condition (10x + y) - (10y + x) = 36.
On solving this we get, (x - y) = 4.
In, the last condition they give, y/x = 1/2.
By solving both above equations we get y = 4.
They ask the value for,(10x + y) - (10x - y).
Which is equal to 2y.
Put the value of y.
We get final value = 8.
Then according to first condition (10x + y) - (10y + x) = 36.
On solving this we get, (x - y) = 4.
In, the last condition they give, y/x = 1/2.
By solving both above equations we get y = 4.
They ask the value for,(10x + y) - (10x - y).
Which is equal to 2y.
Put the value of y.
We get final value = 8.
(3)
Rishitha said:
9 years ago
Can anyone explain what happens after 12k = 48 and 21k = 84?
After we do this how do we get the final answer?
After we do this how do we get the final answer?
Naina said:
8 years ago
Good Explanation, Thanks @KCS.
AMIT RANJAN said:
8 years ago
Suppose we take two nos as X & Y,
then, 10X+Y-10Y-X=36
=> 9X-9y=36 =>X-Y=4 ---> (A)
Given, X:Y = 1:2 => X = Y/2
Now from eq (A) , Y/2 - Y = 4 => -Y/2 = 4 => Y= -8 ---> (B)
A/Q, (X + Y) - (X - Y) = ?
=> X + Y - X + Y= ? => 2Y = ? ---> (C)
So from (B) putting the value of 'Y' in (C),
2Y = 2 * (-8) = -16 ANS.
then, 10X+Y-10Y-X=36
=> 9X-9y=36 =>X-Y=4 ---> (A)
Given, X:Y = 1:2 => X = Y/2
Now from eq (A) , Y/2 - Y = 4 => -Y/2 = 4 => Y= -8 ---> (B)
A/Q, (X + Y) - (X - Y) = ?
=> X + Y - X + Y= ? => 2Y = ? ---> (C)
So from (B) putting the value of 'Y' in (C),
2Y = 2 * (-8) = -16 ANS.
Abi said:
7 years ago
Where is the 9 from? Please explain.
Ajeya said:
7 years ago
Lets assume n1=10a+b and n2 = a+10b where a and b are digits in a two digit number,given n1-n2 = 36,
So, 10a+b-a-10b = 36,
9a-9b = 36,
a-b = 4.
How can it be 8? Please help.
So, 10a+b-a-10b = 36,
9a-9b = 36,
a-b = 4.
How can it be 8? Please help.
Anju said:
7 years ago
Since they have mentioned the word "difference" in the problem so the answer will be 8 .From the 1st part of the question we can find that X-Y=4, also they have mentioned X/Y=1/2 hence Y=2X;
Therefore X~2X=4;hence X=4;Y=8;
So, the answer is :(4+8)~(4~8)=8.
Therefore X~2X=4;hence X=4;Y=8;
So, the answer is :(4+8)~(4~8)=8.
(2)
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