The CAS Registry Mumber 126683-77-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,6,6,8 and 3 respectively; the second part has 2 digits, 7 and 7 respectively. Calculate Digit Verification of CAS Registry Number 126683-77: (8*1)+(7*2)+(6*6)+(5*6)+(4*8)+(3*3)+(2*7)+(1*7)=150 150 % 10 = 0 So 126683-77-0 is a valid CAS Registry Number.