Question

Given

A A A

+ A A

--------------

A B B

If $B\le 5$, what is possible value of B?

• A. $2$
• B. $4$
• C. $2$ or $4$
• D. $0,2$ or $4$

Answer 1

The correct option is C $2$ or $4$

A A A
+ A A
A B B
Which means no carry over, thus A will be smaller than 5 and hence B will be smaller than 9.
If B $\le$ 5, then B = 0, 2 or 4 (2 $\times$ A ) but B cannot be 0,

so B = 2 or 4. (option C)