The CAS Registry Mumber 5524-45-8 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 5,5,2 and 4 respectively; the second part has 2 digits, 4 and 5 respectively. Calculate Digit Verification of CAS Registry Number 5524-45: (6*5)+(5*5)+(4*2)+(3*4)+(2*4)+(1*5)=88 88 % 10 = 8 So 5524-45-8 is a valid CAS Registry Number.