1.

6. The sum of the digits of a two-digit number is 11. If we interchangethe digits then the new number formed is 45 less than the original. Findthe original number.​

Answer»

AnswEr:-

Two digit number = 83

\rule{250}{1}

Let the digit at UNIT's place be m & digit at ten's place be n

ORIGINAL number = m + 10n

Case 1:-

m + n = 11 [Eq.1]

Case 2:-

Interchanged number :-

⇒ New number = n + 10m

According to question:-

⇒ Original number - New number = 45

⇒ m + 10n - (n + 10m) = 45

⇒ m + 10n - n - 10m = 45

⇒ 9n - 9m = 45

⇒ 9(n - m) = 45

⇒ n - m = 45/9

n - m = 5 [Eq.2]

Now ADDING both equations:-

\qquad\sf{n \: + \:  \cancel{m} = 11}

\qquad\sf{n \: - \: \cancel{m} = 5}

\quad\sf{\: (+) \: \: (-) \: \: (+)}

\: \: \rule{100}{1}

\qquad\sf{\: 2n = \:\: 16}

\twoheadrightarrow\sf {\: \: \: \: \:   n = 16/2}

\twoheadrightarrow\sf{\: \: \: \: \: n =\large {\boxed{\sf\green{<klux>8</klux>}}}}

So, digit at ten's place = 8

Put this value in (Eq.2)

⇒ 8 - m = 5

⇒ m = 8 - 5

m = 3

So, digit at unit's place = 3

Now number:-

⇒ Original number = 3 + 10(8)

⇒ Original number = 3 + 80

Original number = 83

Therefore,

\therefore{\underline{\boxed{\textsf{Original number = {\textbf{83 }}}}}}



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