Aptitude - Problems on Numbers - Discussion
Discussion Forum : Problems on Numbers - General Questions (Q.No. 5)
5.
A two-digit number is such that the product of the digits is 8. When 18 is added to the number, then the digits are reversed. The number is:
Answer: Option
Explanation:
| Let the ten's and unit digit be x and | 8 | respectively. |
| x |
| Then, |  |
10x + | 8 |  |
+ 18 = 10 x | 8 | + x |
| x | x |
10x2 + 8 + 18x = 80 + x2
9x2 + 18x - 72 = 0
x2 + 2x - 8 = 0
(x + 4)(x - 2) = 0
x = 2.
Discussion:
42 comments Page 4 of 5.
SK.Gopinath Siva said:
1 decade ago
Let me explain the simplest way.
The way is,
Let take two digit no as x and y.
x * y = 8.
xy + 18 = yx.
//xy = 8// .
8+18 = yx.
yx = 24.
The way is,
Let take two digit no as x and y.
x * y = 8.
xy + 18 = yx.
//xy = 8// .
8+18 = yx.
yx = 24.
Dinesh said:
1 decade ago
@Vijay.
Its very simple.
See the no 9 is divisible by only 3 (other than 1 & itself not to be considered).
So to make 7*5462 divisible by 9, * must be 0 or 3.
Trying with 0 fails to give the ans so then try with 3 it gives u the correct answer.
Its very simple.
See the no 9 is divisible by only 3 (other than 1 & itself not to be considered).
So to make 7*5462 divisible by 9, * must be 0 or 3.
Trying with 0 fails to give the ans so then try with 3 it gives u the correct answer.
Vijay said:
1 decade ago
Find the least value of * for which 7*5462 is divisible by 9?
Please answer the question.
Please answer the question.
Banty kumar.biet davangere said:
1 decade ago
xy=8,xy+18=yx;
put xy=8 than
8+18=24
so,
xy=24 ans
put xy=8 than
8+18=24
so,
xy=24 ans
Manojit said:
1 decade ago
Product of two digit means multiple of two digit.
Suppose two digit is x, y.
Then x*y=8
y=8/x
Now two digit is x, 8/x.
Then look the above problem.
Suppose two digit is x, y.
Then x*y=8
y=8/x
Now two digit is x, 8/x.
Then look the above problem.
Sunny said:
1 decade ago
Why didn't you take 8x, 1/x and solve the problem?
May said:
1 decade ago
Oh. You great and feeling in so easy. Thanks you.
Sudheer said:
1 decade ago
Products of 8 is 2*4, 4*2, 8*1, 1*8.
But he is telling by adding 18 to it the digits are reversed means 24+18=42.
24 is changed to 42. So, the answer is 24.
But he is telling by adding 18 to it the digits are reversed means 24+18=42.
24 is changed to 42. So, the answer is 24.
Shanthi said:
1 decade ago
It is very simple. You can get answer from the options itself. 18+18=36 no. Not reversed. Tak 24+18=42 no. Reversed. 24 is reversed as 42.
Sun said:
1 decade ago
We can directly check out the answer through options.
24 + 18 = 42 which gives product 8.
24 + 18 = 42 which gives product 8.
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