The CAS Registry Mumber 63765-70-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,3,7,6 and 5 respectively; the second part has 2 digits, 7 and 0 respectively. Calculate Digit Verification of CAS Registry Number 63765-70: (7*6)+(6*3)+(5*7)+(4*6)+(3*5)+(2*7)+(1*0)=148 148 % 10 = 8 So 63765-70-8 is a valid CAS Registry Number.