The CAS Registry Mumber 70373-50-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,0,3,7 and 3 respectively; the second part has 2 digits, 5 and 0 respectively. Calculate Digit Verification of CAS Registry Number 70373-50: (7*7)+(6*0)+(5*3)+(4*7)+(3*3)+(2*5)+(1*0)=111 111 % 10 = 1 So 70373-50-1 is a valid CAS Registry Number.