The CAS Registry Mumber 135366-47-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,5,3,6 and 6 respectively; the second part has 2 digits, 4 and 7 respectively. Calculate Digit Verification of CAS Registry Number 135366-47: (8*1)+(7*3)+(6*5)+(5*3)+(4*6)+(3*6)+(2*4)+(1*7)=131 131 % 10 = 1 So 135366-47-1 is a valid CAS Registry Number.