In each row and each column exactly one is to be placed - ∴ No. of such matrices =5×4×3×2×1=120 Alternate :
Step-1 : Select any 1 place for 1 's in row 1. Automatically some column will get filled with 0 's. Step-2 : From next now select 1 place for 1 's. Automatically some column will get filled with 0 's. ⇒ Each time one less place will be available for putting 1's. Repeat step-2 till last row. Req. ways =5×4×3×2×1=120