The CAS Registry Mumber 78352-89-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,8,3,5 and 2 respectively; the second part has 2 digits, 8 and 9 respectively. Calculate Digit Verification of CAS Registry Number 78352-89: (7*7)+(6*8)+(5*3)+(4*5)+(3*2)+(2*8)+(1*9)=163 163 % 10 = 3 So 78352-89-3 is a valid CAS Registry Number.