The CAS Registry Mumber 77563-03-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,7,5,6 and 3 respectively; the second part has 2 digits, 0 and 3 respectively. Calculate Digit Verification of CAS Registry Number 77563-03: (7*7)+(6*7)+(5*5)+(4*6)+(3*3)+(2*0)+(1*3)=152 152 % 10 = 2 So 77563-03-2 is a valid CAS Registry Number.