一、选择题(把正确答案的编号填入括号内)。
$37000÷1200=30······(\quad\quad)$
A. 1
B. 0.1
C. 10
D. 100
E. 1000
$37000÷1200=30······(\quad\quad)$
A. 1
B. 0.1
C. 10
D. 100
E. 1000
答案
D
解析
计算$37000÷1200$时,根据商不变规律,将被除数和除数同时除以100,转化为$370÷12$。
计算$370÷12$,商为30,余数为$370 - 12×30 = 10$。
因为被除数和除数同时缩小了100倍,所以原余数需扩大100倍,即$10×100 = 100$。
计算$370÷12$,商为30,余数为$370 - 12×30 = 10$。
因为被除数和除数同时缩小了100倍,所以原余数需扩大100倍,即$10×100 = 100$。
二、在 1、2、6、7 之间加上“+”“−”“×”“÷”和括号,使之结果为 24,你能想出几种不同的填法吗?请你写出来。其实,这就是常见的用扑克牌算“二十四点”的游戏。
答案
(7 + 6 - 1) × 2 = 24
6 × (7 - 2 - 1) = 24
(7 + 1) × (6 ÷ 2) = 24
(6 - 2) × (7 - 1) = 24
答:共有4种不同的填法,分别是上述算式。
6 × (7 - 2 - 1) = 24
(7 + 1) × (6 ÷ 2) = 24
(6 - 2) × (7 - 1) = 24
答:共有4种不同的填法,分别是上述算式。
三、用一只杯子向一只空瓶内倒水,如果倒进3杯水,那么连瓶共重440克;如果倒进5杯水,那么连瓶共重600克。1杯水和1只空瓶各重多少克?
动脑筋
动脑筋
答案
(600 - 440)÷(5 - 3)
= 160÷2
= 80(克)
440 - 80×3
= 440 - 240
= 200(克)
答:1杯水重80克,1只空瓶重200克。
= 160÷2
= 80(克)
440 - 80×3
= 440 - 240
= 200(克)
答:1杯水重80克,1只空瓶重200克。
1. 请你把一个正方形剪成若干块,再拼成等腰直角三角形。
2. 若是两个大小一样的正方形拼在一起,你也能剪拼成等腰直角三角形吗?

(答案在本书中找)
小作文。Look and write.
要求:至少用到3种句型,40个单词。

Winter
It was winter.
Summer
Now it is summer.
2. 若是两个大小一样的正方形拼在一起,你也能剪拼成等腰直角三角形吗?
(答案在本书中找)
小作文。Look and write.
要求:至少用到3种句型,40个单词。
Winter
It was winter.
Summer
Now it is summer.
答案
1. 剪拼方法:将正方形对边中点连线分成4个小正方形,每个小正方形沿对角线剪开得8个等腰直角三角形,将这些三角形的直角顶点相对,斜边朝外拼接,即可拼成等腰直角三角形。
2. 剪拼方法:将两个正方形拼成的长方形沿一条对角线剪开,得到两个直角梯形,把两个直角梯形的非直角腰拼接,可拼成等腰直角三角形;或将每个正方形沿对角线剪成2个等腰直角三角形,共4个,将4个三角形的直角边依次拼接,斜边组成大等腰直角三角形的两条直角边即可。
Winter
It was winter. The weather was very cold. It snowed heavily. Two children played in the snow. They made a big snowman with a hat. They felt very happy.
Summer
Now it is summer. The weather is hot. Some children go swimming in the river. A girl sits on the beach with a swim ring. They enjoy their summer holidays.
2. 剪拼方法:将两个正方形拼成的长方形沿一条对角线剪开,得到两个直角梯形,把两个直角梯形的非直角腰拼接,可拼成等腰直角三角形;或将每个正方形沿对角线剪成2个等腰直角三角形,共4个,将4个三角形的直角边依次拼接,斜边组成大等腰直角三角形的两条直角边即可。
Winter
It was winter. The weather was very cold. It snowed heavily. Two children played in the snow. They made a big snowman with a hat. They felt very happy.
Summer
Now it is summer. The weather is hot. Some children go swimming in the river. A girl sits on the beach with a swim ring. They enjoy their summer holidays.
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