Question

5. The one's digit of a two digit number is double the digit in the tens place. If the sum of the digits
is 9. find the number.​

Answer 1

Given :

• The one's digit of a two digit number is double the digit in the tens place.

• The sum of the digits is 9.

To find :

• The number =?

Step-by-step explanation :

Let the ten's digit number be x.

Then, the one's digit number be 2x.

It is Given that :

The one's digit of a two digit number is double the digit in the tens place.

So, Required number = x × 10 + 2x.

According to the question :

➮ x + 2x = 9

➮ 3x = 9

➮ x = 9/3

➮ x = 3.

Therefore,

Required number = x × 10 + 2x

            = 3 × 10 + 2 × 3

            = 36

Answer 2

Question:

The one's digit of a two digit number is double the digit in the tens place. If the sum of the digits  is 9. find the number.​

$\bf{\underline{\underline{Solution:}}}$

Let tens place be $\red{\sf{a}}$

Now

According to the question:

One's digit of a two digit number is double the digit in the tens place.

So,

ones place digit = $\red{\sf{2a}}$

Now,

Given in the question that,

Sum of the digits is 9.

→ $\red{\sf{a}}$ + $\red{\sf{2a}}$ = 9

→ $\red{\sf{3a}}$ = 9

→ $\red{\sf{a}}$ = 9 ÷ 3

→ $\red{\sf{a}}$ = 3

So,

Tens digit place = $\red{\sf{a}}$ = 3

And

Ones digit place = $\red{\sf{2a}}$ = 2 × 3 = 6

Hence,

The required two digit number = $\blue{\boxed{\boxed{\sf{36}}}}$