The CAS Registry Mumber 87413-14-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,7,4,1 and 3 respectively; the second part has 2 digits, 1 and 4 respectively. Calculate Digit Verification of CAS Registry Number 87413-14: (7*8)+(6*7)+(5*4)+(4*1)+(3*3)+(2*1)+(1*4)=137 137 % 10 = 7 So 87413-14-7 is a valid CAS Registry Number.