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A 2 digit no is 18 …

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A 2 digit no is 18 such that produces of it's digit is 18 when 3 is subtracted from the no digit interchange their places find the no.
  • 1 answers

Gaurav Seth 4 years, 9 months ago

Let the tens place digit be x.

And the units place digit be y.

According to the Question,

⇒ xy = 18

⇒ y = 18/x .....(i)

And, (10x + y) - 63 = 10y + x

⇒ 9x - 9y = 63

⇒ x - y = 7 .... (ii)

Putting y's value in Eq (ii), we get

⇒ x - 18/x = 7

⇒ x² - 18 = 7x

⇒ x² - 7x - 18 = 0

⇒ x² - 9x + 2x - 18 = 0

⇒x(x - 9) + 2(x - 9) = 0

⇒ (x - 9) (x + 2) = 0

⇒ x - 9 = 0 or x + 2 = 0

⇒ x = 9, - 2 (As x can't be negative)

⇒ x = 9

Putting x's value in Eq (i), we get

⇒ xy = 18

⇒ 9y = 18

⇒ y = 18/9

⇒ y = 2

Number = 92

Hence, the required number is 92.

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