a + b—— b + a |
a x (b x c)——(a x b) x c |
a x c + b x c——(a x b) x c |
=(41+159)+216 =200+216 =416 |
=45x2x8
=90x8
=720 |
=12x5x13
=60x13
=780 |
=230-(76+124)
=230-200
=30
|
=19x(1+99)
=19x100
=1900 |
=(256-56)x9 =200x9 =1800 |
116 | 18900 | 69 |
左边得数 | 右边得数 |
0 | 123 |
1 | 1234 |
12 | 12345 |
5、 420 ÷ (5 x 6)
= 420 ÷ 30
= 14(天)
|
6、(38 + 39 + ...... + 51) ÷ 20
= 860 ÷ 20
= 43(千克)
|
7、(1)
一共要用32 × 3 + 158 × 2 =412(元)。
|
(2)
买床头灯和吸顶灯一共要用多少元?
21 x 4 + 56 x 6
= 84 + 336
= 420(元)
|