The CAS Registry Mumber 90605-22-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,0,6,0 and 5 respectively; the second part has 2 digits, 2 and 2 respectively. Calculate Digit Verification of CAS Registry Number 90605-22: (7*9)+(6*0)+(5*6)+(4*0)+(3*5)+(2*2)+(1*2)=114 114 % 10 = 4 So 90605-22-4 is a valid CAS Registry Number.