如题所述
第1个回答 2021-08-04
=72×(80-1)
=72×80-72×1
=5760-72
=5688
=72×80-72×1
=5760-72
=5688
第2个回答 2021-08-04
72×79
=(70+2)×(80-1)
=70×80-70×1+2×80-2×1
=5600-70+160-2
=5688
=(70+2)×(80-1)
=70×80-70×1+2×80-2×1
=5600-70+160-2
=5688
第3个回答 2021-08-04
72×79
=72×(80-1)
=72×80-72
=5760-72
=5688
=72×(80-1)
=72×80-72
=5760-72
=5688
第4个回答 2021-08-04
第5个回答 2021-08-05
从这两个数字一看就有两个70把两个70分出来
72*79
= 70*(2+9)
=70*2+70*9
=140+630
=770
72*79
= 70*(2+9)
=70*2+70*9
=140+630
=770