The CAS Registry Mumber 370-23-0 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, 2 and 3 respectively. Calculate Digit Verification of CAS Registry Number 370-23: (5*3)+(4*7)+(3*0)+(2*2)+(1*3)=50 50 % 10 = 0 So 370-23-0 is a valid CAS Registry Number.