The CAS Registry Mumber 70143-25-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,0,1,4 and 3 respectively; the second part has 2 digits, 2 and 5 respectively. Calculate Digit Verification of CAS Registry Number 70143-25: (7*7)+(6*0)+(5*1)+(4*4)+(3*3)+(2*2)+(1*5)=88 88 % 10 = 8 So 70143-25-8 is a valid CAS Registry Number.