The CAS Registry Mumber 130857-42-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,0,8,5 and 7 respectively; the second part has 2 digits, 4 and 2 respectively. Calculate Digit Verification of CAS Registry Number 130857-42: (8*1)+(7*3)+(6*0)+(5*8)+(4*5)+(3*7)+(2*4)+(1*2)=120 120 % 10 = 0 So 130857-42-0 is a valid CAS Registry Number.