The CAS Registry Mumber 59857-56-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,9,8,5 and 7 respectively; the second part has 2 digits, 5 and 6 respectively. Calculate Digit Verification of CAS Registry Number 59857-56: (7*5)+(6*9)+(5*8)+(4*5)+(3*7)+(2*5)+(1*6)=186 186 % 10 = 6 So 59857-56-6 is a valid CAS Registry Number.