The CAS Registry Mumber 204448-37-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,0,4,4,4 and 8 respectively; the second part has 2 digits, 3 and 7 respectively. Calculate Digit Verification of CAS Registry Number 204448-37: (8*2)+(7*0)+(6*4)+(5*4)+(4*4)+(3*8)+(2*3)+(1*7)=113 113 % 10 = 3 So 204448-37-3 is a valid CAS Registry Number.