The CAS Registry Mumber 77745-22-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,7,7,4 and 5 respectively; the second part has 2 digits, 2 and 2 respectively. Calculate Digit Verification of CAS Registry Number 77745-22: (7*7)+(6*7)+(5*7)+(4*4)+(3*5)+(2*2)+(1*2)=163 163 % 10 = 3 So 77745-22-3 is a valid CAS Registry Number.