The CAS Registry Mumber 1000312-84-4 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,0,0,0,3,1 and 2 respectively; the second part has 2 digits, 8 and 4 respectively. Calculate Digit Verification of CAS Registry Number 1000312-84: (9*1)+(8*0)+(7*0)+(6*0)+(5*3)+(4*1)+(3*2)+(2*8)+(1*4)=54 54 % 10 = 4 So 1000312-84-4 is a valid CAS Registry Number.