In the four-digit number ABCD, each letter represents a unique integer. When A is multiplied by B, the product is odd. When A is multiplied by C, the product is even. Which of the following four-digit numbers is even?

A. ABDC

B. CABD

C. ACDB

D. Cannot be determined from the information given.

A

Step-by-step explanation:

Nice problem.

The only way you can get an odd number by multiplying two digits together is if they are both odd.

For example 5*7 = 35 which is odd. You cannot find 2 odd numbers that when multiplied will give an even.

That means that A and B are both odd.

Now if you multiply an odd and an even together, you always get an even.

For example 4 * 9 = 36 which is even.

Since A is known to be odd, C must be even. So the four digit number you want ends in C.

The Answer is A