The CAS Registry Mumber 1217443-77-0 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,2,1,7,4,4 and 3 respectively; the second part has 2 digits, 7 and 7 respectively. Calculate Digit Verification of CAS Registry Number 1217443-77: (9*1)+(8*2)+(7*1)+(6*7)+(5*4)+(4*4)+(3*3)+(2*7)+(1*7)=140 140 % 10 = 0 So 1217443-77-0 is a valid CAS Registry Number.