The CAS Registry Mumber 372-03-2 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 2 respectively; the second part has 2 digits, 0 and 3 respectively. Calculate Digit Verification of CAS Registry Number 372-03: (5*3)+(4*7)+(3*2)+(2*0)+(1*3)=52 52 % 10 = 2 So 372-03-2 is a valid CAS Registry Number.