Question

If the digit 1 is placed after a two digit number whose tens digit is ‘t’ and units digit is ‘u’, which of these options represents the new number?

• A. $10t+u+1$
• B. $100t+10u+1$
• C. $t+u+1$
• D. $\text{none of these}$

Answer 1

The correct option is B

$100t+10u+1$

The two digit number is 'tu'.

After placing '1' as indicated in the problem, the new number becomes 'tu1'.

So, ‘t’ is now in the hundred's place and ‘u’ is now in the ten's place. '1' is in unit's place.

Therefore, the number is
$100t+10u+1$.