The CAS Registry Mumber 88730-40-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,8,7,3 and 0 respectively; the second part has 2 digits, 4 and 0 respectively. Calculate Digit Verification of CAS Registry Number 88730-40: (7*8)+(6*8)+(5*7)+(4*3)+(3*0)+(2*4)+(1*0)=159 159 % 10 = 9 So 88730-40-9 is a valid CAS Registry Number.