The CAS Registry Mumber 28941-59-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,8,9,4 and 1 respectively; the second part has 2 digits, 5 and 9 respectively. Calculate Digit Verification of CAS Registry Number 28941-59: (7*2)+(6*8)+(5*9)+(4*4)+(3*1)+(2*5)+(1*9)=145 145 % 10 = 5 So 28941-59-5 is a valid CAS Registry Number.