The CAS Registry Mumber 214355-27-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,1,4,3,5 and 5 respectively; the second part has 2 digits, 2 and 7 respectively. Calculate Digit Verification of CAS Registry Number 214355-27: (8*2)+(7*1)+(6*4)+(5*3)+(4*5)+(3*5)+(2*2)+(1*7)=108 108 % 10 = 8 So 214355-27-8 is a valid CAS Registry Number.