The CAS Registry Mumber 31038-07-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 3,1,0,3 and 8 respectively; the second part has 2 digits, 0 and 7 respectively. Calculate Digit Verification of CAS Registry Number 31038-07: (7*3)+(6*1)+(5*0)+(4*3)+(3*8)+(2*0)+(1*7)=70 70 % 10 = 0 So 31038-07-0 is a valid CAS Registry Number.