The CAS Registry Mumber 370-74-1 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 3,7 and 0 respectively; the second part has 2 digits, 7 and 4 respectively. Calculate Digit Verification of CAS Registry Number 370-74: (5*3)+(4*7)+(3*0)+(2*7)+(1*4)=61 61 % 10 = 1 So 370-74-1 is a valid CAS Registry Number.