1.

Unit's digits of a 2 digit number is 5 more than the ten's digit, and if we put the digits of the number in reverse order, the new number is 4 less than twice the original number. The number is :-1). 272). 493). 724). 38

Answer»

Let the digits of the number be a and b.

∴ the number is 10A + b

Given Unit's digits of a 2 digit number is 5 more than the ten's digit

∴ b = 5 + a-----[1]

On reversing the digits number OBTAINED = 10b + a

Now, this number is 4 less than TWICE the original number

∴ 2(10a + b) – (10b + a) = 4

⇒ 19a – 8b = 4 -----[2]

Putting the value of b = 5 + a from equation [1] in equation [2]

⇒ 19a – 40 – 8a = 4

⇒ 11a = 44

⇒ a = 44/11 = 4

∴ b = 5 + a

= 5 + 4

= 9

The original number is 49


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