巧算:100+99-98-97+96+95-·····+4+3-2-1

问题描述:

巧算:100+99-98-97+96+95-·····+4+3-2-1

100+99-98-97+96+95-·····+4+3-2-1
=(100+99-98-97)+(96+96-94-93)+……(4+3-2-1)
=4+4+……+4
=4×25
=100

100+99-98-97+96+95-·····+4+3-2-1
=(100-98)+(99-97)+、、、+(4-2)+(3-1)
=2+2+.+2+2
=2x50
=100