The CAS Registry Mumber 84050-23-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,4,0,5 and 0 respectively; the second part has 2 digits, 2 and 3 respectively. Calculate Digit Verification of CAS Registry Number 84050-23: (7*8)+(6*4)+(5*0)+(4*5)+(3*0)+(2*2)+(1*3)=107 107 % 10 = 7 So 84050-23-7 is a valid CAS Registry Number.