The CAS Registry Mumber 170458-89-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,7,0,4,5 and 8 respectively; the second part has 2 digits, 8 and 9 respectively. Calculate Digit Verification of CAS Registry Number 170458-89: (8*1)+(7*7)+(6*0)+(5*4)+(4*5)+(3*8)+(2*8)+(1*9)=146 146 % 10 = 6 So 170458-89-6 is a valid CAS Registry Number.