The CAS Registry Mumber 138850-04-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,8,8,5 and 0 respectively; the second part has 2 digits, 0 and 4 respectively. Calculate Digit Verification of CAS Registry Number 138850-04: (8*1)+(7*3)+(6*8)+(5*8)+(4*5)+(3*0)+(2*0)+(1*4)=141 141 % 10 = 1 So 138850-04-1 is a valid CAS Registry Number.