The CAS Registry Mumber 126899-15-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,6,8,9 and 9 respectively; the second part has 2 digits, 1 and 5 respectively. Calculate Digit Verification of CAS Registry Number 126899-15: (8*1)+(7*2)+(6*6)+(5*8)+(4*9)+(3*9)+(2*1)+(1*5)=168 168 % 10 = 8 So 126899-15-8 is a valid CAS Registry Number.