The CAS Registry Mumber 54837-22-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,4,8,3 and 7 respectively; the second part has 2 digits, 2 and 2 respectively. Calculate Digit Verification of CAS Registry Number 54837-22: (7*5)+(6*4)+(5*8)+(4*3)+(3*7)+(2*2)+(1*2)=138 138 % 10 = 8 So 54837-22-8 is a valid CAS Registry Number.