The CAS Registry Mumber 70958-65-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,0,9,5 and 8 respectively; the second part has 2 digits, 6 and 5 respectively. Calculate Digit Verification of CAS Registry Number 70958-65: (7*7)+(6*0)+(5*9)+(4*5)+(3*8)+(2*6)+(1*5)=155 155 % 10 = 5 So 70958-65-5 is a valid CAS Registry Number.