The CAS Registry Mumber 76659-40-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,6,6,5 and 9 respectively; the second part has 2 digits, 4 and 0 respectively. Calculate Digit Verification of CAS Registry Number 76659-40: (7*7)+(6*6)+(5*6)+(4*5)+(3*9)+(2*4)+(1*0)=170 170 % 10 = 0 So 76659-40-0 is a valid CAS Registry Number.