The CAS Registry Mumber 126568-77-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,6,5,6 and 8 respectively; the second part has 2 digits, 7 and 7 respectively. Calculate Digit Verification of CAS Registry Number 126568-77: (8*1)+(7*2)+(6*6)+(5*5)+(4*6)+(3*8)+(2*7)+(1*7)=152 152 % 10 = 2 So 126568-77-2 is a valid CAS Registry Number.