如何用简便方法计算(脱式)
99×21 25×36 125×48 25×(40+4)
第1个回答 2016-03-19
追答
写纸上的,
本回答被提问者采纳第2个回答 2016-03-19
第3个回答 2016-03-19
99×21
=(100-1)×21
=100×21-1×21
=2100-21
=2079
25×36
=25×(4×9)
=25×4×9
=100×9
=900
125×48
=125×(8×6)
=125×8×6
=1000×6
=6000
25×(40+4)
=25×40+25×4
=1000+100
=110追答
=(100-1)×21
=100×21-1×21
=2100-21
=2079
25×36
=25×(4×9)
=25×4×9
=100×9
=900
125×48
=125×(8×6)
=125×8×6
=1000×6
=6000
25×(40+4)
=25×40+25×4
=1000+100
=110追答
最后一道题1100
追问Thank you very much
追答thanks
第4个回答 2016-03-19
(100-1)×21
=100×21-1×21
=2100-21
=2079
25×36
=5×5×6×6
=5×6×5×6
=30×30
=900
125×48
=5×25×6×8
=25×8×5×6
=200×30
=6000
25×(40+4)
=25×40+25×4
=1000+100
=1100
=100×21-1×21
=2100-21
=2079
25×36
=5×5×6×6
=5×6×5×6
=30×30
=900
125×48
=5×25×6×8
=25×8×5×6
=200×30
=6000
25×(40+4)
=25×40+25×4
=1000+100
=1100