The CAS Registry Mumber 57026-64-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,7,0,2 and 6 respectively; the second part has 2 digits, 6 and 4 respectively. Calculate Digit Verification of CAS Registry Number 57026-64: (7*5)+(6*7)+(5*0)+(4*2)+(3*6)+(2*6)+(1*4)=119 119 % 10 = 9 So 57026-64-9 is a valid CAS Registry Number.