The CAS Registry Mumber 59770-97-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,9,7,7 and 0 respectively; the second part has 2 digits, 9 and 7 respectively. Calculate Digit Verification of CAS Registry Number 59770-97: (7*5)+(6*9)+(5*7)+(4*7)+(3*0)+(2*9)+(1*7)=177 177 % 10 = 7 So 59770-97-7 is a valid CAS Registry Number.