The CAS Registry Mumber 55230-27-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,5,2,3 and 0 respectively; the second part has 2 digits, 2 and 7 respectively. Calculate Digit Verification of CAS Registry Number 55230-27: (7*5)+(6*5)+(5*2)+(4*3)+(3*0)+(2*2)+(1*7)=98 98 % 10 = 8 So 55230-27-8 is a valid CAS Registry Number.