The CAS Registry Mumber 1848-74-4 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 1,8,4 and 8 respectively; the second part has 2 digits, 7 and 4 respectively. Calculate Digit Verification of CAS Registry Number 1848-74: (6*1)+(5*8)+(4*4)+(3*8)+(2*7)+(1*4)=104 104 % 10 = 4 So 1848-74-4 is a valid CAS Registry Number.