The CAS Registry Mumber 67600-18-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,7,6,0 and 0 respectively; the second part has 2 digits, 1 and 8 respectively. Calculate Digit Verification of CAS Registry Number 67600-18: (7*6)+(6*7)+(5*6)+(4*0)+(3*0)+(2*1)+(1*8)=124 124 % 10 = 4 So 67600-18-4 is a valid CAS Registry Number.