Question

a two digit number is less than 20 the sum of the digit is double that of their product what is the number​

Answer 1

Let the numbers be x and y.
x+y = 2xy
x(2y-1) = y
x = y/(2y-1). Here if y=1, x=1.
Thus the number = 11.

Answer 2

${\large{\fcolorbox{aqua}{navy}{\fcolorbox{yellow}{blue}{\bf{\color{yellow}{⫷Question⫸}}}}}}$

A two digit number is less than 20. The sum of the digit is double that of their product. What is the number?

${\large{\fcolorbox{aqua}{navy}{\fcolorbox{yellow}{blue}{\bf{\color{yellow}{⫷Given⫸}}}}}}$

• The two digit number is less than 20.
• The sum of the digit is double that of their product.

${\large{\fcolorbox{aqua}{navy}{\fcolorbox{yellow}{blue}{\bf{\color{yellow}{⫷Solution⫸}}}}}}$

Let the ones digit be x.

Since the number is of 2 -digits and is less than 20, it's tens digit must be 1.

So,

2×1×x = x+1

⇒2x = x+1

⇒2x-x = 1

⇒x = 1

So, x = 1.

The number

= (10×1)+x

= 10+x

Substitute x with 1.

10+x

= 10+1

= 11

${\large{\fcolorbox{aqua}{navy}{\fcolorbox{yellow}{blue}{\bf{\color{yellow}{⫷Therefore⫸}}}}}}$

The number is 11.

$\bold{\boxed{{\blue{✿}}{\pink{H}}{\blue{O}}{\green{P}}{\red{E}}{\purple{  }}{\orange{T}}{\pink{H}}{\blue{I}}{\green{S}}{\red{  }}{\purple{H}}{\orange{E}}{\pink{L}}{\blue{P}}{\green{S}}{\red{  }}{\purple{Y}}{\orange{O}}{\pink{U}}{\blue{✿}}}}$

$\bold{\boxed{{\blue{✿}}{\pink{H}}{\blue{A}}{\green{V}}{\red{E}}{\purple{  }}{\orange{A}}{\pink{  }}{\blue{N}}{\green{I}}{\red{C}}{\purple{E}}{\purple{  }}{\orange{D}}{\pink{A}}{\green{Y}}{\blue{✿}}}}$