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  1. The sum of the digits of a two digit number is 10, when the number is reversed, the number increases by 72.Find the number.
    1. 64
    2. 82
    3. 19
    4. 37
Correct Option: C

By checking options
91-19=72

Or

Let the number be xy
So 10x + y = 10 ..... (i)

When the number is reversed the new number is yx
So (10y + 10 ) - ( 10x +y ) = 72 ....(ii)

From Eqs. (i) & (ii)
x = 1 and y =9
∴number = 19


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