for i in range(1,10):
for j in range(1,i+1):
print("%dX%d=%-2d"%(i,j,i*j),end=" ")
print()
1X1=1
2X1=2 2X2=4
3X1=3 3X2=6 3X3=9
4X1=4 4X2=8 4X3=12 4X4=16
5X1=5 5X2=10 5X3=15 5X4=20 5X5=25
6X1=6 6X2=12 6X3=18 6X4=24 6X5=30 6X6=36
7X1=7 7X2=14 7X3=21 7X4=28 7X5=35 7X6=42 7X7=49
8X1=8 8X2=16 8X3=24 8X4=32 8X5=40 8X6=48 8X7=56 8X8=64
9X1=9 9X2=18 9X3=27 9X4=36 9X5=45 9X6=54 9X7=63 9X8=72 9X9=81
关键点：for循环嵌套，格式化，print函数。
