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99×9+99用简便计算

99×9+99 =99×(9+1) =99×10 =990

解:9+99+999+9999 =(10-1)+(100-1)+(1000-1)+(10000-1) =11110-4 =11106 解析:9+99+999+9999+99999,运用加法的运算性质,把接近整十、整百、整千、…,看作与它接近的整十、整百、整千…;进行计算,多加几再减去几。 主要考查对加法交...

有两种思路 1)90 × 9 + 9 × 9 = 810 + 81 =891 2)(100 - 1) × 9 =900 - 9 = 891

99.9×99.9 =99.9×(100-0.1) =99.9×100-99.9×0.1 =9990-9.99 =9980.01 99.9×99.9 =(100-0.1)² =10000-20+0.01 =9980+0.01 =9980.01

原式 =9.99×(1+99) =9.99×100 =999

解:19.9+9.99×9 =19.9+9.99x(10-1) =19.9+99.9-9.99 =20-0.1+100-0.1-10+0.01 =110+0.01-0.2 =109.8+0.01 =109.81

解:根据提取公因式的简便方法, 应是=67x9+9x(11x3) =67x9+9x33 =9x(67+33) =9x100 =900

99x999+199 =99x999+99+100 =99x(999+1)+100 =99x1000+100 =99000+100 =99100

67×9+99×3 =67×9+33×9 =(67+33)×9 =100×9 =900 67×9+99×3 =67×3×3+99×3 =(201+99)×3 =300×3 =900 67×9+99×3 =67×(10-1)+3×(100-1) =670-67+300-3 =970-70 =900

(100一0.1)X(10一0.1)+9.99 =100X10+100X0.1一0.1X10一0.1X(一0.1)+9.99 =1000+10一1+0.01+9.99 =1000+10一1+(0.01+9.99) =1000+10一1+10 =1019

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