The CAS Registry Mumber 5570-85-4 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 5,5,7 and 0 respectively; the second part has 2 digits, 8 and 5 respectively. Calculate Digit Verification of CAS Registry Number 5570-85: (6*5)+(5*5)+(4*7)+(3*0)+(2*8)+(1*5)=104 104 % 10 = 4 So 5570-85-4 is a valid CAS Registry Number.