The CAS Registry Mumber 87449-78-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,7,4,4 and 9 respectively; the second part has 2 digits, 7 and 8 respectively. Calculate Digit Verification of CAS Registry Number 87449-78: (7*8)+(6*7)+(5*4)+(4*4)+(3*9)+(2*7)+(1*8)=183 183 % 10 = 3 So 87449-78-3 is a valid CAS Registry Number.