The CAS Registry Mumber 72290-31-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,2,2,9 and 0 respectively; the second part has 2 digits, 3 and 1 respectively. Calculate Digit Verification of CAS Registry Number 72290-31: (7*7)+(6*2)+(5*2)+(4*9)+(3*0)+(2*3)+(1*1)=114 114 % 10 = 4 So 72290-31-4 is a valid CAS Registry Number.