The CAS Registry Mumber 67384-54-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,7,3,8 and 4 respectively; the second part has 2 digits, 5 and 4 respectively. Calculate Digit Verification of CAS Registry Number 67384-54: (7*6)+(6*7)+(5*3)+(4*8)+(3*4)+(2*5)+(1*4)=157 157 % 10 = 7 So 67384-54-7 is a valid CAS Registry Number.