The CAS Registry Mumber 10587-31-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,0,5,8 and 7 respectively; the second part has 2 digits, 3 and 1 respectively. Calculate Digit Verification of CAS Registry Number 10587-31: (7*1)+(6*0)+(5*5)+(4*8)+(3*7)+(2*3)+(1*1)=92 92 % 10 = 2 So 10587-31-2 is a valid CAS Registry Number.