1+2+3+4+5+6+7+8+9+.+99999+100000=
问题描述:
1+2+3+4+5+6+7+8+9+.+99999+100000=
答
1+2+3+4+5+6+7+8+9+.+99999+100000=
=(1+100000)×100000÷2
=100001×50000
=5000050000