The CAS Registry Mumber 80770-70-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,0,7,7 and 0 respectively; the second part has 2 digits, 7 and 0 respectively. Calculate Digit Verification of CAS Registry Number 80770-70: (7*8)+(6*0)+(5*7)+(4*7)+(3*0)+(2*7)+(1*0)=133 133 % 10 = 3 So 80770-70-3 is a valid CAS Registry Number.