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:
46 comments Page 5 of 5.
Manu said:
1 decade ago
Why are you taking (10*2x+x) - (10+2x) = 36? Please explain it.
Priya said:
1 decade ago
Can anyone explain why do we take (y+x)-(y-x) in the last step rather than 10x+y-(10y-x) ?
Deepak said:
1 decade ago
In the first condition, we get,
10x+y-(10y-x) = 36.
So, 9x-9y = 36.
By solving this we get x-y = 4. Thats all.
10x+y-(10y-x) = 36.
So, 9x-9y = 36.
By solving this we get x-y = 4. Thats all.
Leopard said:
1 decade ago
Let's the digits are x & y.
The ratio between them is x:y = 1:2.
So y=2x.
Hence y is ten digit no.
According to statement,
(10y+x)-(10x+y) = 36.
(10*2x+x)-(10x+2x) = 36.
21x-12x = 36.
9x = 36.
x = 4..
(y+x)-(y-x) = (2x+4)-(2x-4).
= (8+4)-(8-4).
= 12-4 = 8.
The ratio between them is x:y = 1:2.
So y=2x.
Hence y is ten digit no.
According to statement,
(10y+x)-(10x+y) = 36.
(10*2x+x)-(10x+2x) = 36.
21x-12x = 36.
9x = 36.
x = 4..
(y+x)-(y-x) = (2x+4)-(2x-4).
= (8+4)-(8-4).
= 12-4 = 8.
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
Let,
x = 2a
y = a
Then,
a = 4
Difference =
(8 + 4) - ( 8 - 4)
12 - 4 = 8
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
Let,
x = 2a
y = a
Then,
a = 4
Difference =
(8 + 4) - ( 8 - 4)
12 - 4 = 8
Kcs said:
1 decade ago
Two digits x&y
x:y=1:2
x=k
y=2k
two numbers 10x+y&10y+x
10x+y=10k+2k=12k
10y+x=20k+k=21k
diff=9k=36
k=4
numbers 12k=48
21k=84
sum of dgts=12
diff of dgts=4
ans=sum-diff=8
x:y=1:2
x=k
y=2k
two numbers 10x+y&10y+x
10x+y=10k+2k=12k
10y+x=20k+k=21k
diff=9k=36
k=4
numbers 12k=48
21k=84
sum of dgts=12
diff of dgts=4
ans=sum-diff=8
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers