Question

42✘102-82怎样算简便？

Answer 1

42×102-82
＝42×（100＋2）-82
＝42×100＋42×2-82
＝4200＋84-82
＝4200＋（84-82）
＝4200＋2
＝4202

Answer 2

42×102-82
＝42×102-42×2
＝42×(102-2)
＝42×100
＝4200

Answer 3

42×102-82=42×（100+2）-82
=4200+84-82
=4202

Answer 4

=42×(100+2)－82=4200+84－82=4202

Answer 5

42×102-82
=42×100+42×2-82
=4200+84-82
=4200+2
=4202