The CAS Registry Mumber 80121-70-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,0,1,2 and 1 respectively; the second part has 2 digits, 7 and 0 respectively. Calculate Digit Verification of CAS Registry Number 80121-70: (7*8)+(6*0)+(5*1)+(4*2)+(3*1)+(2*7)+(1*0)=86 86 % 10 = 6 So 80121-70-6 is a valid CAS Registry Number.