The CAS Registry Mumber 141957-45-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,4,1,9,5 and 7 respectively; the second part has 2 digits, 4 and 5 respectively. Calculate Digit Verification of CAS Registry Number 141957-45: (8*1)+(7*4)+(6*1)+(5*9)+(4*5)+(3*7)+(2*4)+(1*5)=141 141 % 10 = 1 So 141957-45-1 is a valid CAS Registry Number.