The CAS Registry Mumber 90053-41-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,0,0,5 and 3 respectively; the second part has 2 digits, 4 and 1 respectively. Calculate Digit Verification of CAS Registry Number 90053-41: (7*9)+(6*0)+(5*0)+(4*5)+(3*3)+(2*4)+(1*1)=101 101 % 10 = 1 So 90053-41-1 is a valid CAS Registry Number.