The CAS Registry Mumber 82961-65-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,2,9,6 and 1 respectively; the second part has 2 digits, 6 and 5 respectively. Calculate Digit Verification of CAS Registry Number 82961-65: (7*8)+(6*2)+(5*9)+(4*6)+(3*1)+(2*6)+(1*5)=157 157 % 10 = 7 So 82961-65-7 is a valid CAS Registry Number.