The CAS Registry Mumber 100763-81-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,0,7,6 and 3 respectively; the second part has 2 digits, 8 and 1 respectively. Calculate Digit Verification of CAS Registry Number 100763-81: (8*1)+(7*0)+(6*0)+(5*7)+(4*6)+(3*3)+(2*8)+(1*1)=93 93 % 10 = 3 So 100763-81-3 is a valid CAS Registry Number.