The CAS Registry Mumber 157487-33-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,5,7,4,8 and 7 respectively; the second part has 2 digits, 3 and 3 respectively. Calculate Digit Verification of CAS Registry Number 157487-33: (8*1)+(7*5)+(6*7)+(5*4)+(4*8)+(3*7)+(2*3)+(1*3)=167 167 % 10 = 7 So 157487-33-7 is a valid CAS Registry Number.