1+2+3+······99=100X()=()
11个回答

1+2+3+······99=100X(49.5)=(4950)

解法:分组为1+99,2+98,等等,共49*组,还剩一个数是50,所以1+2+3+······99=49x100+50

56+57+58+59+60+61+62+63+64=(60)X(9)=(540)

解法:56+64=60+60,57+63=60+60,以此类推

确保完全正确,