Latihan tambahan

一半 = separuh 两个盒子一样大，A 装满时的数量是参照数，B 只装了一半。估计 B 的数量，就是求参照数的一半，也就是把参照数除以 2。 例子：满盒 600 支笔，同样大的盒子装一半，大约 300 支。 注意：一半是除以 2，不是乘 2；估计的数一定比装满时少。

half = separuh The boxes are the same size. Box A's full amount is the reference, and box B is half full. To estimate B, find half of the reference by dividing by 2. Example: a full box holds 600 pens, so a same-size box half full holds about 300. Watch out: half means divide by 2, not multiply, and the estimate must be less than a full box.

几车的数量 = bilangan beberapa lori 一辆罗厘能载的西瓜数是参照数。西瓜堆大约有几车那么多，就用“车数 × 每车的数量”来估计。 例子：一辆巴士约 40 人，大约 4 辆巴士就是 4 × 40，大约 160 人。 注意：车数和每车数量要相乘，不是相加；也不要把两个数字直接拼在一起。

how many lorries = bilangan beberapa lori One lorry load is the reference. If the heap is about a few lorry loads, estimate with number of lorries × amount per lorry. Example: one bus carries about 40 people, so about 4 buses carry about 4 × 40 = 160. Watch out: multiply the number of lorries by the load, do not add them or join the digits.

快满了 = hampir penuh 题目给出容器装满时的数量，问“快满”时哪个估计合理。“快满”表示比装满时少一点，但很接近。所以合理的估计要同时符合两点：比装满的数量小，又和它很接近。 例子：满瓶 800 毫升，快满时估计 700 毫升较合理；估计 300 毫升太少，估计 1 100 毫升比满瓶还多。 注意：比装满还多的估计一定不合理；只有一半左右的估计也太少。

nearly full = hampir penuh The full amount is given; which estimate fits a nearly full container? Nearly full means a little less than full but close to it. A reasonable estimate is smaller than the full amount and close to it. Example: a full bottle holds 800 ml, so nearly full is about 700 ml; 300 ml is too little and 1 100 ml is more than full. Watch out: an estimate above the full amount is never reasonable, and about half is far too little.

参照物的用处 = kegunaan set rujukan 题目问估计时为什么要用参照物。想一想：参照物是我们已经知道数量的东西。把要估计的量和它比一比，看是它的一半、差不多，还是几倍，估计出来的数就有根据。 例子：知道一个纸箱装 24 瓶水，看到一堆大约 5 箱，就能说大约 120 瓶。 注意：好的参照物要数量已知，而且和要估计的东西大小差不多。

why use a reference = kegunaan set rujukan Why do we use a reference set when estimating? A reference is something whose amount we already know. Comparing with it, as half, about the same or a few times as much, gives the estimate a reason. Example: knowing a carton holds 24 bottles, a stack of about 5 cartons holds about 120 bottles. Watch out: a good reference has a known amount and is similar in size to what we estimate.