Question 1:
A A is equal to 5 because 5 is the only one digit number that when
A tripled, gives the same digit in the ones place.
+ A
-----
B A
5
5
+ 5
-----
1 5
Question 11:
A B B cannot be 0 because then A would then also be equal to 0 (B+B=A,
+ A B ones column). B cannot be 3 or greater because this would make A
------- carry over, giving a 3-digit number.
C A
4 2 2 1
+ 4 2 or + 2 1
------- -------
8 4 4 2
Question 12:
A B B is equal to half of C and A is equal to double B. A has to be
+ A B smaller than 5 otherwise the sum would be a 3-digit number. B can
------- only equal to 2 or 4 because they are the only numbers that can be
B C equally divided into A in the tens column.
2 4 1 2
+ 2 4 or + 1 2
------- -------
4 8 2 4
Question 23:
A B A A can only be 5 because 5 is the only one digit number that when
A B A multiplied by 5 has the same units digit as the starting number
A B A (5x5=25). In the tens column B can only be 7 because when
A B A multiplied by 5 and added to the carried over number i.e. 2, gives
+ A B A the sum of the starting digit (7x5+2=37).
----------
C D B A
5 7 5
5 7 5
5 7 5
5 7 5
+ 5 7 5
----------
2 8 7 5
By Monique Madsen