The CAS Registry Mumber 57976-43-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,7,9,7 and 6 respectively; the second part has 2 digits, 4 and 3 respectively. Calculate Digit Verification of CAS Registry Number 57976-43: (7*5)+(6*7)+(5*9)+(4*7)+(3*6)+(2*4)+(1*3)=179 179 % 10 = 9 So 57976-43-9 is a valid CAS Registry Number.