The CAS Registry Mumber 5633-22-7 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 5,6,3 and 3 respectively; the second part has 2 digits, 2 and 2 respectively. Calculate Digit Verification of CAS Registry Number 5633-22: (6*5)+(5*6)+(4*3)+(3*3)+(2*2)+(1*2)=87 87 % 10 = 7 So 5633-22-7 is a valid CAS Registry Number.