The CAS Registry Mumber 106689-70-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,6,6,8 and 9 respectively; the second part has 2 digits, 7 and 0 respectively. Calculate Digit Verification of CAS Registry Number 106689-70: (8*1)+(7*0)+(6*6)+(5*6)+(4*8)+(3*9)+(2*7)+(1*0)=147 147 % 10 = 7 So 106689-70-7 is a valid CAS Registry Number.