Determine the total number of quadruplets (A,B, C, D) of positive integers with A ≤ B ≤ C ≤ D ≤ 25, such that (A+B)*(C+D) is divisible by |A*D – B*C|, whenever A*D ≠ B*C.

__Note__: |x| refers to the

**absolute value** of x.

(In reply to

computer solution by Charlie)

**Do me a favor , Charlie**

**I'®ve tried to evaluate ***manually* the **total number of quadruplets (A,B, C, D) of positive integers with A <= B <= C <= D <= 25, and got 20175.**

**Tot= C(25,4)+25*C(24,2)+2*C(25,2)+25=20175**

**Please, check my result by adding another counter to your program and make me happy (or busy again).**

**Thank you**.

*Edited on ***February 7, 2011, 1:59 am**