The CAS Registry Mumber 850544-48-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 8,5,0,5,4 and 4 respectively; the second part has 2 digits, 4 and 8 respectively. Calculate Digit Verification of CAS Registry Number 850544-48: (8*8)+(7*5)+(6*0)+(5*5)+(4*4)+(3*4)+(2*4)+(1*8)=168 168 % 10 = 8 So 850544-48-8 is a valid CAS Registry Number.