The CAS Registry Mumber 90689-37-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,0,6,8 and 9 respectively; the second part has 2 digits, 3 and 7 respectively. Calculate Digit Verification of CAS Registry Number 90689-37: (7*9)+(6*0)+(5*6)+(4*8)+(3*9)+(2*3)+(1*7)=165 165 % 10 = 5 So 90689-37-5 is a valid CAS Registry Number.