The CAS Registry Mumber 442632-40-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 4,4,2,6,3 and 2 respectively; the second part has 2 digits, 4 and 0 respectively. Calculate Digit Verification of CAS Registry Number 442632-40: (8*4)+(7*4)+(6*2)+(5*6)+(4*3)+(3*2)+(2*4)+(1*0)=128 128 % 10 = 8 So 442632-40-8 is a valid CAS Registry Number.