Question

$\begin{array}{cc}1728& \\ +B& \\ 172C& \end{array}$
B =___; C =___

Answer 1

Since we have first 3 digits in answer as 172, i.e., same as the first three digits of number 1728, we can be sure that there is no carry after the addition 8 + B.

For 8 + B = C with no carry, B can only be 1. If it's 2, there will be 1 carry.

Since B = 1; 1728 + 1 = 1729

So, C = 9.