| 简便计算. 216+305 25×32 47+236+64 6×(15×9)402+359 43+78+122+257 25×(26×4)25×44 354+(229+46) |
| ①216+305, =200+16+300+5, =200+300+16+5, =500+21, =521; ②25×32, =25×4×8, =800; ③47+236+64, =47+(64+236), =47+300, =347; ④6×(15×9), =6×15×9, =90×9, =810; ⑤402+539, =400+(2+539), =400+541, =941; ⑥43+78+122+257, =(43+257)+(78+122), =300+200, =500; ⑦25×(26×4), =25×4×26, =100×26, =2600; ⑧25×44, =25×4×11, =100×11, =1100; ⑨354+(229+46), =354+46+229, =400+229, =629; |
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