9.8×25简便运算
=（10-0.2）x25
=10x25-0.2x25
=250+5
=255
10*2.5-0.2*2.5=25-0.5=24.5
9.8×25=245
回答完毕~
有疑问请追问~无疑问请点击【采纳】~
祝学习进步\(^o^)/~~~
9.8x25
=（10-0.2）x25
=10x25-0.2x25
=250-5
=245
2.96x40
=（3-0.04）x40
=3x40-0.04x40
=120-1.6
=118.4
①9.8×2.5
=（10-0.2）×2.5
=10×2.5-0.2×2.5
=25-0.5
=24.5
②3.8×9.9+0.1×3.8
=3.8×（9.9+0.1）
=3.8×10
=38
③3.42×99+3.42
=3.42×（99+1）
=3.42×100
=342
8.5×9.8
=8.5×(10-0.2）
=85-1.7
=83.3
7.23*9.8=7.23*10-7.23*0.2=72.3-1.446=70.854
望采纳
9.4X9.8
=9.4X（10-0.2）
=9.4X10-9.4X0.2
=94-1.88
=92.12
4.5ⅹ9.8
=4.5×（10-0.2）
=45-0.9
=44.1
简便运算0.82×9.8
0.82×9.8
=0.82*(10-0.2)
=0.82*10-0.82*0.2
=8.036