如题所述
第1个回答 2020-05-07
105x78
=(100十5)ⅹ78
=100x78+5x78
=7800十390
=8190
验算:78x105
=78x(100十5)
=78x100十78x5
=7800十390
=8190
=(100十5)ⅹ78
=100x78+5x78
=7800十390
=8190
验算:78x105
=78x(100十5)
=78x100十78x5
=7800十390
=8190
第2个回答 2020-05-07
105×78=8190
78×105=8190
所以105×78＝78×105
78×105=8190
所以105×78＝78×105
第3个回答 2020-05-07
=（100+5）x78
=7800+390
=8190
=7800+390
=8190
第4个回答 2020-05-08
105×78
=105×(80-2)
=105×80-105×2
=8400-210
=8190
=105×(80-2)
=105×80-105×2
=8400-210
=8190
