The CAS Registry Mumber 75011-20-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,5,0,1 and 1 respectively; the second part has 2 digits, 2 and 0 respectively. Calculate Digit Verification of CAS Registry Number 75011-20: (7*7)+(6*5)+(5*0)+(4*1)+(3*1)+(2*2)+(1*0)=90 90 % 10 = 0 So 75011-20-0 is a valid CAS Registry Number.