The CAS Registry Mumber 76338-09-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,6,3,3 and 8 respectively; the second part has 2 digits, 0 and 9 respectively. Calculate Digit Verification of CAS Registry Number 76338-09: (7*7)+(6*6)+(5*3)+(4*3)+(3*8)+(2*0)+(1*9)=145 145 % 10 = 5 So 76338-09-5 is a valid CAS Registry Number.