Tambah dan Tolak

从左到右 = dari kiri ke kanan 第一步先算左边的加法：31 425 + 2 680 = 34 105；第二步用这个得数做减法：34 105 − 5 370 = 28 735。每一步都用竖式，小心进位和退位。 例子：12 000 + 3 000 − 5 000 = 15 000 − 5 000 = 10 000。 注意：第一步的答案要写下来，第二步才不会用错数。

from left to right = dari kiri ke kanan Step 1, the addition on the left: 31 425 + 2 680 = 34 105. Step 2, subtract from that answer: 34 105 − 5 370 = 28 735. Use a column calculation for each step and watch the carrying and regrouping. Example: 12 000 + 3 000 − 5 000 = 15 000 − 5 000 = 10 000. Watch out: write down the answer to step 1 so you use the right number in step 2.

带着符号换次序 = tukar susunan bersama simbol 可以把“− 5 370”和“+ 2 680”换位置，但符号要跟着它的数走：减的还是减，加的还是加。先减后加，答案一样是 28 735。 例子：900 + 50 − 400 = 900 − 400 + 50 = 550。 注意：只换数字、不换符号，答案就错了。

move each number with its sign = tukar susunan bersama simbol You may swap − 5 370 and + 2 680, but each sign must move with its number: what is subtracted is still subtracted, and what is added is still added. Subtracting first gives the same answer, 28 735. Example: 900 + 50 − 400 = 900 − 400 + 50 = 550. Watch out: swapping the numbers without their signs gives a wrong answer.

找错误 = cari kesilapan 算式是 52 040 − 3 815 + 960。第二种算法把两个数换了位置，却没有把符号一起带过去：本来要加的 960 被减掉，本来要减的 3 815 反而被加上，所以错了。从左到右算，或者换位置时让符号跟着数走，才对。 例子：100 − 20 + 5 = 85；如果写成 100 − 5 + 20 = 115，就是只换了数字、没换符号。 注意：每个数前面的符号是它自己的，换位置时要一起搬。

find the mistake = cari kesilapan The sentence is 52 040 − 3 815 + 960. The second working swaps the two numbers but leaves the signs behind: the 960 that should be added is subtracted, and the 3 815 that should be subtracted is added. Work from left to right, or move each sign with its number. Example: 100 − 20 + 5 = 85; writing 100 − 5 + 20 = 115 swaps the numbers without their signs. Watch out: the sign in front of a number belongs to it and must move with it.

倒过来算 = kerja ke belakang 先用小数字想：□ + 3 − 2 = 6，□ 是多少？倒回去：6 + 2 = 8，8 − 3 = 5，所以 □ = 5；检查 5 + 3 − 2 = 6。大数也是一样。未知数在最前面时，从答案倒着推：最后一步是减 1 450，倒回去就加 1 450，得 21 450；前一步是加 6 238，倒回去就减 6 238，得 15 212。 例子：□ + 30 − 10 = 50 → 50 + 10 = 60，60 − 30 = 30。 注意：倒推时加变减、减变加，次序也要倒过来。

work backwards = kerja ke belakang Think small first: □ + 3 − 2 = 6; going back, 6 + 2 = 8 and 8 − 3 = 5, so □ = 5, and 5 + 3 − 2 = 6 checks. Big numbers work the same way. When the unknown is at the start, work back from the answer. The last step subtracts 1 450, so undo it by adding 1 450 to get 21 450. The step before adds 6 238, so undo it by subtracting 6 238 to get 15 212. Example: □ + 30 − 10 = 50: 50 + 10 = 60, then 60 − 30 = 30. Watch out: when working backwards, adding becomes subtracting and the order is reversed too.

先减后加 = tolak dahulu, kemudian tambah 这是一个有减号又有加号的算式。要从左到右一步一步算：先做左边的符号（减），把得数写下来；再用这个得数做右边的符号（加）。每一步都用竖式，小心借位和进位。 例子：5 000 − 1 200 + 2 400 → 先 5 000 − 1 200 = 3 800，再 3 800 + 2 400 = 6 200。 注意：不能先把减号后面的两个数加起来再一起减，那样会把应该加的数也减掉。

subtract first, then add = tolak dahulu, kemudian tambah This sentence has a minus and a plus. Work from left to right: do the subtraction first and write down the answer, then add to that answer. Use columns and watch the regrouping. Example: 5 000 − 1 200 + 2 400: first 3 800, then 3 800 + 2 400 = 6 200. Watch out: do not add the last two numbers first and take them both away, or the number that should be added gets subtracted.

倒推 = kerja ke belakang 未知数在最前面，后面先加再减，得到结果。可以先用小数字想：□ + 3 − 2 = 6，倒回去 6 + 2 = 8，8 − 3 = 5。做法就是从结果开始倒着走：最后一步是减，倒回去就加；前一步是加，倒回去就减。最后把答案放回原式检查。 例子：□ + 400 − 150 = 1 000 → 1 000 + 150 = 1 150，1 150 − 400 = 750；检查 750 + 400 − 150 = 1 000。 注意：倒推时次序要反过来，从最后一步开始；加变减、减变加。

work backwards = kerja ke belakang The unknown is at the start; something is added, then something is taken away. Think small: □ + 3 − 2 = 6, and going back 6 + 2 = 8, 8 − 3 = 5. Start from the result and undo each step from the last one: undo a subtraction by adding and an addition by subtracting. Check in the sentence. Example: □ + 400 − 150 = 1 000: 1 000 + 150 = 1 150, 1 150 − 400 = 750; check 750 + 400 − 150 = 1 000. Watch out: undo the steps in reverse order, starting from the last one.