Question 64

A number lying between 10 and 100 is seven times the sum of digits. If 9 is subtracted from it, the digits of the number are reversed. The number is

Name: A number lying between 10 and 100 is seven times the sum of digits. If 9 is subtracted from it, the digits of the number are reversed. The number is
Uploaded: 2026-04-27T20:08:41.916297+05:30
Duration: 2 min 52 s
Description: A number lying between 10 and 100 is seven times the sum of digits. If 9 is subtracted from it, the digits of the number are reversed. The number is

Solution

Let the unit's digit is $$y$$ and ten's digit is $$x$$, => Number = $$10x+y$$

=> $$10x+y=7(x+y)$$

=> $$10x+y=7x+7y$$

=> $$3x=6y$$

=> $$x=2y$$ ----------------(i)

Also, $$10x+y-9=10y+x$$

=> $$9(x-y)=9$$

=> $$x-y=1$$

Substituting value from equation (i), => $$2y-y=y=1$$

=> $$x=2$$

$$\therefore$$ Original number = 21

=> Ans - (A)

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