The CAS Registry Mumber 42362-21-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 4,2,3,6 and 2 respectively; the second part has 2 digits, 2 and 1 respectively. Calculate Digit Verification of CAS Registry Number 42362-21: (7*4)+(6*2)+(5*3)+(4*6)+(3*2)+(2*2)+(1*1)=90 90 % 10 = 0 So 42362-21-0 is a valid CAS Registry Number.