The CAS Registry Mumber 77270-37-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,7,2,7 and 0 respectively; the second part has 2 digits, 3 and 7 respectively. Calculate Digit Verification of CAS Registry Number 77270-37: (7*7)+(6*7)+(5*2)+(4*7)+(3*0)+(2*3)+(1*7)=142 142 % 10 = 2 So 77270-37-2 is a valid CAS Registry Number.