The CAS Registry Mumber 87540-93-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,7,5,4 and 0 respectively; the second part has 2 digits, 9 and 3 respectively. Calculate Digit Verification of CAS Registry Number 87540-93: (7*8)+(6*7)+(5*5)+(4*4)+(3*0)+(2*9)+(1*3)=160 160 % 10 = 0 So 87540-93-0 is a valid CAS Registry Number.