The CAS Registry Mumber 88230-37-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,8,2,3 and 0 respectively; the second part has 2 digits, 3 and 7 respectively. Calculate Digit Verification of CAS Registry Number 88230-37: (7*8)+(6*8)+(5*2)+(4*3)+(3*0)+(2*3)+(1*7)=139 139 % 10 = 9 So 88230-37-9 is a valid CAS Registry Number.