The CAS Registry Mumber 110780-72-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,0,7,8 and 0 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 110780-72: (8*1)+(7*1)+(6*0)+(5*7)+(4*8)+(3*0)+(2*7)+(1*2)=98 98 % 10 = 8 So 110780-72-8 is a valid CAS Registry Number.