The CAS Registry Mumber 88043-71-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,8,0,4 and 3 respectively; the second part has 2 digits, 7 and 1 respectively. Calculate Digit Verification of CAS Registry Number 88043-71: (7*8)+(6*8)+(5*0)+(4*4)+(3*3)+(2*7)+(1*1)=144 144 % 10 = 4 So 88043-71-4 is a valid CAS Registry Number.