The CAS Registry Mumber 65594-67-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,5,5,9 and 4 respectively; the second part has 2 digits, 6 and 7 respectively. Calculate Digit Verification of CAS Registry Number 65594-67: (7*6)+(6*5)+(5*5)+(4*9)+(3*4)+(2*6)+(1*7)=164 164 % 10 = 4 So 65594-67-4 is a valid CAS Registry Number.