Question

简便计算2.64＊28+23.9＊7.2？

简便计算2.64＊28+23.9＊7.2

Answer 1

2.64×28+23.9×7.2
＝（2×28+0.6×28+0.04×28）+（20×7.2+4×7.2-0.1×7.2）
＝（56+16.8+1.02）+（144+28.8 -0.72）
＝（72.8+1.08）+（172.8-0.72）
＝73.88+172.728
＝（74+172）+（0.728-0.12）
＝246+0.608
＝246.608

Answer 2

=2.64×28+2.39×72
=2.64×(28+72)－18×(4×0.25)
=264－18×1
=246

追答

=2.64×28+2.39×10×7.2
=2.64×(28+72)－9×(8×0.25)
=264－18
=246

Answer 3

2.64×28＋23.9×7.2
＝2.64×28＋2.39×（100－28）
＝2.64×28＋2.39×100－2.39×28
＝28×（2.64－2.39）＋2.39×100
＝28×0.25＋2.39×100
＝0.28×100/4＋2.39×100
＝100×（0.07＋2.39）
＝100×2.46
＝246

Answer 4

2.64×28+23.9×7.2
=（2.39+0.25）×28+23.9×7.2
=2.39×28+0.25×28+23.9×7.2
=23.9×28÷10+23.9×7.2+7
=23.9×（2.8+7.2）+7
=23.9×10+7
=239+7
=246

Answer 5

2.64*28+23.9*7.2
=26.4*2.8+23.9*7.2
=（23.9+2.5）*2.8+23.9*7.2
=23.9*2.8+2.5*2.8+23.9*7.2
=23.9*（2.8+7.2）+2.5*4*0.7
=23.9*10+10*0.7
=（23.9+0.7）*10
=24.6*10
=246