The CAS Registry Mumber 316358-49-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 3,1,6,3,5 and 8 respectively; the second part has 2 digits, 4 and 9 respectively. Calculate Digit Verification of CAS Registry Number 316358-49: (8*3)+(7*1)+(6*6)+(5*3)+(4*5)+(3*8)+(2*4)+(1*9)=143 143 % 10 = 3 So 316358-49-3 is a valid CAS Registry Number.