Question

What are the value of $A$ and $B$?
$AB$
+$79$
___
$9A$

• A. $A=1,B=1$
• B. $A=2,B=1$
• C. $A=1,B=2$
• D. $A=2,B=0$

Answer 1

Answer: (C)

$A=1,B=2$

$AB$
+$79$
___
$9A$

The addition of $B$ and $9$ gives $A$ i.e., $B+9=A$
The above condition is possible only when digit $A$ is $1$, because $A+7=9$.
$1$ will be the carry for the next step to get the value $9$. i.e.,$1+1+7=9$
So, the value of $A=1$.

The value of $B$ must be $2$, because the value of $A$ is $1$.
$2+9=11$, $1$ will be the carry for the next step.
Therefore, the addition is as follows:
$12$
+ $79$
___
$91$
The value of $A=1,B=2$.