The CAS Registry Mumber 1141855-20-0 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,1,4,1,8,5 and 5 respectively; the second part has 2 digits, 2 and 0 respectively. Calculate Digit Verification of CAS Registry Number 1141855-20: (9*1)+(8*1)+(7*4)+(6*1)+(5*8)+(4*5)+(3*5)+(2*2)+(1*0)=130 130 % 10 = 0 So 1141855-20-0 is a valid CAS Registry Number.