The CAS Registry Mumber 849-19-4 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 8,4 and 9 respectively; the second part has 2 digits, 1 and 9 respectively. Calculate Digit Verification of CAS Registry Number 849-19: (5*8)+(4*4)+(3*9)+(2*1)+(1*9)=94 94 % 10 = 4 So 849-19-4 is a valid CAS Registry Number.