1.

1). 982). 893). 784). 87

Answer»

Let the tens and UNITS DIGITS of the NUMBER be X and y respectively

x × y = 72

⇒ y = 72/x

10x + y + 9 = 10y + x

9Y – 9x = 9

⇒ 72/x – x = 1

⇒ x2 + x – 72 = 0

⇒ (x + 9)(x – 8) = 0

⇒ x = 8

y = 72/8 = 9

∴ Number is 89



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