The CAS Registry Mumber 4372-37-6 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,3,7 and 2 respectively; the second part has 2 digits, 3 and 7 respectively. Calculate Digit Verification of CAS Registry Number 4372-37: (6*4)+(5*3)+(4*7)+(3*2)+(2*3)+(1*7)=86 86 % 10 = 6 So 4372-37-6 is a valid CAS Registry Number.