The CAS Registry Mumber 13487-45-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,3,4,8 and 7 respectively; the second part has 2 digits, 4 and 5 respectively. Calculate Digit Verification of CAS Registry Number 13487-45: (7*1)+(6*3)+(5*4)+(4*8)+(3*7)+(2*4)+(1*5)=111 111 % 10 = 1 So 13487-45-1 is a valid CAS Registry Number.