Latest Elitmus Aptitude Question SOLUTION: consider a two digit number "ab". square the number and divide the resultant by half of the numer. then add 18 in the resultant. and then divide by 2 the resultant. How many number

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(#M40164725) ELITMUS Numerical Ability question Keep an EYE

consider a two digit number "ab". square the number and divide the resultant by half of the numer. then add 18 in the resultant. and then divide by 2 the resultant. How many numbers are possible that it reversing the digit ex. "ba".

option:
A. 7
B. 8
C. 9
D. one more option I don't remember

Asked In Elitmus Sahil Tanwar (6 years ago)

Unsolved Read Solution (8)

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Read Solution (8) :

Wali Nusker  (6 years ago)

If the number is ab. Then it will be 10a+b.
Square it => (10a+b)^2
Divide by half the number => [(10a+b)^2] / [(10a+b)/2] => 2(10a+b)
Add 18 => 2(10a+b) + 18
Divide by 2 => (10a+b) + 9

This is equal to reverse of the number so => 10b+a
Equate them-
10a+b+9 = 10b+a
9a-9b = -9
b - a = 1

So we see the condition is :- (one's digit) - (tens digit) = 1
So there are 8 possibilities- 12, 23, 34, 45, 56, 67, 78, 89.

Is this solution Helpfull? Yes (36) | No (5)  

sachin Bohra  (6 years ago)

simple....
1. x=the number
2. x^2 and divide it by x/2
3. we get 2x
4. add 18 we get 2x+18
5. divide by 2 we get x+9
6. now use hit and trial
7. 12+9=21
23+9=32
34+9=43
.
.
.
89+9=98
8. so total possible number are=8

Is this solution Helpfull? Yes (3) | No (6)  

Shubham Jain  (6 years ago)

B.....My answer is my explaination

Is this solution Helpfull? Yes (1) | No (8)  

Sayantan Das  (6 years ago)

ans: 9

ab+9=ba

01+9=10
12+9=21
23+9=32
34+9=43
.
.
89+9=98

Is this solution Helpfull? Yes (1) | No (4)  

Shushank   (6 years ago)

D...................NO EXPLANATION

Is this solution Helpfull? Yes | No (6)  

ghost  (6 years ago)

Answer: 8
((ab)^2/ab + 18)/ 2 = ab + 9
now ab + 9 = ba
ab = 10a + b
ba = 10b + a
10a + b + 9 = 10b + a
9a - 9b + 9 = 0
b = a + 1
now assuming base 10 number system is used
so a can be [1, 8] not including 0 and 9 so to satisfy above conditions and a cant be 0 as to make it two digit number
so a can assume only 8 possible values between 0 to 8

Is this solution Helpfull? Yes | No (2)  

Divya Batra  (6 years ago)

B.
possible numbers are
12,23,34,45,56,67,78,89

Is this solution Helpfull? Yes | No (1)  

Kumari sanjana  (6 years ago)

anwer will be 8 as we cannot consider 01+9=10 coz den 01 will not be 2 digit number. read the 1st sentence its written ab is 2 digit no.

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