问几个速算题2X999+2+999X4+4+6+6X9993X998+6+4X998+8+6X998+124X995+2
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问几个速算题
2X999+2+999X4+4+6+6X999
3X998+6+4X998+8+6X998+12
4X995+20+5X996+20+6X997X18
5X999+3X998+997+14
2X999+2+999X4+4+6+6X999
3X998+6+4X998+8+6X998+12
4X995+20+5X996+20+6X997X18
5X999+3X998+997+14
![问几个速算题2X999+2+999X4+4+6+6X9993X998+6+4X998+8+6X998+124X995+2](/uploads/image/z/18992309-5-9.jpg?t=%E9%97%AE%E5%87%A0%E4%B8%AA%E9%80%9F%E7%AE%97%E9%A2%982X999%2B2%2B999X4%2B4%2B6%2B6X9993X998%2B6%2B4X998%2B8%2B6X998%2B124X995%2B2)
都是根据乘法分配律做得,乘法分配律:ab+ac=a(b+c)
①原式=2×999+2×1+4×999+4×1+6×1+6×999
=2×(999+1)+4×(999+1)+6×(999+1)
=2×1000+4×1000+6×1000
=(2+4+6)×1000
=12×1000
=12000
②原式=3×998+3×2+4×998+4×2+6×998+6×2
=3×(998+2)+4×(998+2)+6×(998+2)
=(3+4+6)×1000
=13000
③原式=4×995+4×5+5×996+5×4+6×997+6×3
=4×(995+5)+5×(996+4)+6×(997+3)
=(4+5+6)×1000
=15000
④原式=5×999+3×998+997+(5+3×2+3)
=5×(999+1)+3×(998+2)+(997+3)
=(5+3+1)×1000
=9000
①原式=2×999+2×1+4×999+4×1+6×1+6×999
=2×(999+1)+4×(999+1)+6×(999+1)
=2×1000+4×1000+6×1000
=(2+4+6)×1000
=12×1000
=12000
②原式=3×998+3×2+4×998+4×2+6×998+6×2
=3×(998+2)+4×(998+2)+6×(998+2)
=(3+4+6)×1000
=13000
③原式=4×995+4×5+5×996+5×4+6×997+6×3
=4×(995+5)+5×(996+4)+6×(997+3)
=(4+5+6)×1000
=15000
④原式=5×999+3×998+997+(5+3×2+3)
=5×(999+1)+3×(998+2)+(997+3)
=(5+3+1)×1000
=9000
999^2-1002X998 有没有什么简便计算
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