The CAS Registry Mumber 75487-17-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,5,4,8 and 7 respectively; the second part has 2 digits, 1 and 7 respectively. Calculate Digit Verification of CAS Registry Number 75487-17: (7*7)+(6*5)+(5*4)+(4*8)+(3*7)+(2*1)+(1*7)=161 161 % 10 = 1 So 75487-17-1 is a valid CAS Registry Number.