The CAS Registry Mumber 151453-17-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,5,1,4,5 and 3 respectively; the second part has 2 digits, 1 and 7 respectively. Calculate Digit Verification of CAS Registry Number 151453-17: (8*1)+(7*5)+(6*1)+(5*4)+(4*5)+(3*3)+(2*1)+(1*7)=107 107 % 10 = 7 So 151453-17-7 is a valid CAS Registry Number.