用简便方法计算.9999×7778+3333×666623+23×5+25×7+27×9+29×11+211×13.-六年级数学

题目简介

用简便方法计算.9999×7778+3333×666623+23×5+25×7+27×9+29×11+211×13.-六年级数学

题目详情

用简便方法计算.
9999×7778+3333×6666
2
3
+
2
3×5
+
2
5×7
+
2
7×9
+
2
9×11
+
2
11×13
题型:解答题难度:中档来源:不详

答案

(1)9999×7778+3333×6666
=9999×7778+3333×3×2222
=9999×7778+9999×2222
=9999×(7778+2222)
=9999×10000
=99990000

(2)class="stub"2
3
+class="stub"2
3×5
+class="stub"2
5×7
+class="stub"2
7×9
+class="stub"2
9×11
+class="stub"2
11×13

=2×(class="stub"1
3
+class="stub"1
3
-class="stub"1
5
+class="stub"1
5
-class="stub"1
7
+class="stub"1
7
-class="stub"1
9
+class="stub"1
9
-class="stub"1
11
+class="stub"1
11
-class="stub"1
13

=2×(class="stub"2
3
-class="stub"1
13

=class="stub"1
3
-class="stub"2
13

=class="stub"7
39

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