The CAS Registry Mumber 50900-22-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,0,9,0 and 0 respectively; the second part has 2 digits, 2 and 2 respectively. Calculate Digit Verification of CAS Registry Number 50900-22: (7*5)+(6*0)+(5*9)+(4*0)+(3*0)+(2*2)+(1*2)=86 86 % 10 = 6 So 50900-22-6 is a valid CAS Registry Number.