Question

In a two digits number the unit digits is twice the ten's digit . if 27 is added to the number the digits interchange their places find the number​

Answer 1

Answer:

36

Explanation:

Let unit's digit =x and ten's digit =y

∴ Number =10y+x

Reverse number =10x+y

According to the question

2y=x...(i)

10y+x+27=10x+y ...(ii)

⇒10y+2y+27=20y+y

12y−21y=−27

−9y=−27⇒y=3

x=6

∴Number=36

you can also solve this by another method

Let ten’s digit = x

Unit’s digit = 2x

Required number = 10x + 2x = 12x

On interchanging the digits

Number formed = 10(2x) + x

= 21x

According given condition

12x + 27 = 21x

27 = 21x – 12x

27 = 9x

∴ x = 27 /9

x = 3

∴ Required number = 12 × 13

= 36

Answer 2

Given :-

•Unit digit is twice the ten's digit .

•If 27 is added to the number the digits interchange their places.

To Find :-

• What's the number ?

Solution :-

As per question :-

Given that,

Unit digit is twice the ten's digit .

Let ten's place digit be x.

Therefore, unit's place digit will be 2x.

Again, it’s given that

If 27 is added to the number the digits interchange their places.

⟼ 12x+27 = 21x

⟼ 27 = 21x−12x

⟼ 27 = 9x

$⟼x = 3$

Hence,

ten's place digit is = x = 3

Units place digit is = 2x = 2×3 = 6

Therefore, the number will be

= 30 + 6

= 36