The CAS Registry Mumber 74770-45-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,4,7,7 and 0 respectively; the second part has 2 digits, 4 and 5 respectively. Calculate Digit Verification of CAS Registry Number 74770-45: (7*7)+(6*4)+(5*7)+(4*7)+(3*0)+(2*4)+(1*5)=149 149 % 10 = 9 So 74770-45-9 is a valid CAS Registry Number.