Question

Unit digit of a $2$-digit number is $3$ times its tens digit. If the unit digit is $6$, find the number.

Answer 1

Step 1: Finding the tens digits.

Given : Unit digit $=6$

Since we know that a two digit number whose unit digit and tens digit are $\mathrm{x}$ and $\mathrm{y}$ respectively $=10\mathrm{y}+\mathrm{x}$ $\dots .....\left(\mathrm{i}\right)$

So, according to given condition the unit digit number is $3$ times its tens digit,

$\therefore \mathrm{x}=3\mathrm{y}$

Now we have unit digit i.e., $\mathrm{x}=6$

$$\begin{gathered} \Rightarrow \mathrm{x}=3\mathrm{y} \\ \Rightarrow 6=3\mathrm{y} \\ \Rightarrow \frac{6}{3}=\mathrm{y} \\ \Rightarrow \mathrm{y}=2 \end{gathered}$$

Therefore, tens digit of the number is $2$.

Step 2: Finding the number.

Now, tens digit $=2$ and unit digit $=6$

Since, the two-digit number is $=10\mathrm{y}+\mathrm{x}$

$$\begin{gathered} =10\times 2+6 \\ =20+6 \\ =26 \end{gathered}$$

Hence, the number is $26$.