One simple argument

T_100=5050,is clearly divisible by 5+5=10
T_1000=500500,
...
T_10^{k+1}=50...050...0, with k zeros sandwiched between the two 5's and another k zeros trailing the second 5, which is clearly divisible by 10 for all k>=1.

所有跟帖： 

• 回复：One simple argument -cma- ♂ (18 bytes) () 10/21/2009 postreply 19:37:07

• like this one -乱弹- ♂ (0 bytes) () 10/21/2009 postreply 20:13:19