The CAS Registry Mumber 42385-90-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 4,2,3,8 and 5 respectively; the second part has 2 digits, 9 and 0 respectively. Calculate Digit Verification of CAS Registry Number 42385-90: (7*4)+(6*2)+(5*3)+(4*8)+(3*5)+(2*9)+(1*0)=120 120 % 10 = 0 So 42385-90-0 is a valid CAS Registry Number.