Question

The sum of a two digit number and the number obtained by interchangeing it's digit is 99 . Find the number​

Answer 1

$\sf\huge {\underline{\underline{{Solution}}}}$

since, we don't know the numbers so,let us assume the ten's digit be 'x'

and unit digit be 'y'

Original number formed = 10x +y

Number formed after interchanging it's digit => 10y+x

according to the question:

sum of two digit numbers and the number obtained by interchanging it's digit is 99

then our Equation becomes

=> 10x+y+10y+x=99

=>11x+11y=99

=> 11(x+y)=99

=>x+y= 9

Since , we only obtained one Equation so,the numbers can be 18,81, 54,45,27,72,36,63 etc

Concept

the unit place must be greater than the ten's place only if our answer be correct.

let's take the number 18. Here, 8 -1 is 7, but 1-8 is - 7 also 8+1 is also 9 so the given answer is correct.

Answer 2

Answer:

since, we don't know the numbers so,let us assume the ten's digit be 'x'

and unit digit be 'y'

Original number formed = 10x +y

Number formed after interchanging it's digit => 10y+x

according to the question:

sum of two digit numbers and the number obtained by interchanging it's digit is 99

then our Equation becomes

=> 10x+y+10y+x=99

=>11x+11y=99

=> 11(x+y)=99

=>x+y= 9

Since , we only obtained one Equation so,the numbers can be 18,81, 54,45,27,72,36,63 etc

Concept

the unit place must be greater than the ten's place only if our answer be correct.

let's take the number 18. Here, 8 -1 is 7, but 1-8 is - 7 also 8+1 is also 9 so the given answer is correct.

Step-by-step explanation:

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