The CAS Registry Mumber 11006-72-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,1,0,0 and 6 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 11006-72: (7*1)+(6*1)+(5*0)+(4*0)+(3*6)+(2*7)+(1*2)=47 47 % 10 = 7 So 11006-72-7 is a valid CAS Registry Number.