Aptitude - Problems on Numbers - Discussion
Discussion Forum : Problems on Numbers - General Questions (Q.No. 9)
9.
In a two-digit, if it is known that its unit's digit exceeds its ten's digit by 2 and that the product of the given number and the sum of its digits is equal to 144, then the number is:
Answer: Option
Explanation:
Let the ten's digit be x.
Then, unit's digit = x + 2.
Number = 10x + (x + 2) = 11x + 2.
Sum of digits = x + (x + 2) = 2x + 2.
(11x + 2)(2x + 2) = 144
22x2 + 26x - 140 = 0
11x2 + 13x - 70 = 0
(x - 2)(11x + 35) = 0
x = 2.
Hence, required number = 11x + 2 = 24.
Discussion:
42 comments Page 4 of 5.
Moti Chavan said:
8 years ago
Yes, right @Pratyasha.
The 2 digit number is represented as 10x+y. But by taking like this I'm not getting answer.
The 2 digit number is represented as 10x+y. But by taking like this I'm not getting answer.
Sabu said:
7 years ago
11x2 + 13x - 70 = 0.
(x - 2)(11x + 35) = 0.
x = 2.
How does this do?
(x - 2)(11x + 35) = 0.
x = 2.
How does this do?
(3)
Siddhesh said:
7 years ago
The product of the given number and sum of digit means;
24 * (2+4) = 144.
So, the answer is 24.
24 * (2+4) = 144.
So, the answer is 24.
(19)
Gurleen said:
7 years ago
Not clear. Please explain in an easy way.
(1)
Tejaswi said:
7 years ago
2 digit number can be represented as 10x+y.
Let's take a 2-digit number 52.
it can be written as 50+2.
50=10*5.
So "10 * 5 +2" (10x+y).
Let's take a 2-digit number 52.
it can be written as 50+2.
50=10*5.
So "10 * 5 +2" (10x+y).
(1)
Vishnu s said:
7 years ago
@All.
If the 10th place be denoted by 10x then unit place exceeds 2 more than the 10th place then unit place value should be denoted as 10x+2 why they denote x+2 for the unit place. Please explain this.
If the 10th place be denoted by 10x then unit place exceeds 2 more than the 10th place then unit place value should be denoted as 10x+2 why they denote x+2 for the unit place. Please explain this.
(2)
GAURAV said:
6 years ago
This type of problem doesn't gives a correct answers, as question sentences are itself confusing.
(4)
Ayushi said:
6 years ago
Hi, Can anyone tell me, how we get (22x^2 + 26x - 140)?
Prashasti said:
5 years ago
Thanks @Amrith.
(1)
Joel said:
3 years ago
@Ayushi.
=(11x+2)(2x+2)=144 (Multiplication with both values 11x => 2x & 2 and 2 => 2x & 2).
=>22x^2+22x+4x+4 = 144,
22x^2+26x+4-144 = 0,
22x^2+26x-140=0/squaring this value.
11x2 + 13x - 70 = 0.
We get.
(x - 2)(11x + 35) = 0,
x = 2.
=(11x+2)(2x+2)=144 (Multiplication with both values 11x => 2x & 2 and 2 => 2x & 2).
=>22x^2+22x+4x+4 = 144,
22x^2+26x+4-144 = 0,
22x^2+26x-140=0/squaring this value.
11x2 + 13x - 70 = 0.
We get.
(x - 2)(11x + 35) = 0,
x = 2.
(2)
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