7+8=几用手脑速算需图解?

2024-12-15 00:58:15
推荐回答(1个)
回答1:

解兄凳:
7+8=15
7+8
=7+(3+5)
=(羡厅旅7+3)+5
=10+5
=15
7+8
=(伏郑5+2)+8
=5+(2+8)
=5+10
=15