14. Xiao Ming puts several chess pieces into the small squares of a $3 * 3$ grid. Each small square can be left empty or can contain one or more chess pieces. Now, by counting the total number of chess pieces in each row and each column, 6 numbers are obtained, and these 6 numbers are all different. What is the minimum number of chess pieces needed?
【Answer】 8
Analysis: Trying the smallest sum $0+1+2+3+4+5=15$, since the sum of the three rows = the sum of the three columns = the total sum, 15 is not an even number, so $16 \div 2=8,8=0+2+6=1+3+4$, after trials, it can be placed as shown in the figure, then the minimum number of chess pieces needed is 8