The CAS Registry Mumber 40678-98-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 4,0,6,7 and 8 respectively; the second part has 2 digits, 9 and 8 respectively. Calculate Digit Verification of CAS Registry Number 40678-98: (7*4)+(6*0)+(5*6)+(4*7)+(3*8)+(2*9)+(1*8)=136 136 % 10 = 6 So 40678-98-6 is a valid CAS Registry Number.