The CAS Registry Mumber 106270-20-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,6,2,7 and 0 respectively; the second part has 2 digits, 2 and 0 respectively. Calculate Digit Verification of CAS Registry Number 106270-20: (8*1)+(7*0)+(6*6)+(5*2)+(4*7)+(3*0)+(2*2)+(1*0)=86 86 % 10 = 6 So 106270-20-6 is a valid CAS Registry Number.