The CAS Registry Mumber 170006-88-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,7,0,0,0 and 6 respectively; the second part has 2 digits, 8 and 8 respectively. Calculate Digit Verification of CAS Registry Number 170006-88: (8*1)+(7*7)+(6*0)+(5*0)+(4*0)+(3*6)+(2*8)+(1*8)=99 99 % 10 = 9 So 170006-88-9 is a valid CAS Registry Number.