The CAS Registry Mumber 502442-90-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 5,0,2,4,4 and 2 respectively; the second part has 2 digits, 9 and 0 respectively. Calculate Digit Verification of CAS Registry Number 502442-90: (8*5)+(7*0)+(6*2)+(5*4)+(4*4)+(3*2)+(2*9)+(1*0)=112 112 % 10 = 2 So 502442-90-2 is a valid CAS Registry Number.