The CAS Registry Mumber 84040-75-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,4,0,4 and 0 respectively; the second part has 2 digits, 7 and 5 respectively. Calculate Digit Verification of CAS Registry Number 84040-75: (7*8)+(6*4)+(5*0)+(4*4)+(3*0)+(2*7)+(1*5)=115 115 % 10 = 5 So 84040-75-5 is a valid CAS Registry Number.