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换算 = tukar 先把 ribu 和 ratus 换成普通的数，再相减。千位以下是 0 的时候，减去几百就要向千位借位：千位少 1，百位变成 10 再减。 例子：12 ribu − 3 ratus = 12 000 − 300 = 11 700。 注意：ratus 是百，不是千；把 ratus 当成 ribu 来减，答案会小很多。

change the words = tukar Change ribu and ratus into ordinary numbers, then subtract. When the places below the thousands are 0, taking away hundreds means borrowing from the thousands: the thousands go down by 1 and the hundreds become 10. Example: 12 ribu − 3 ratus = 12 000 − 300 = 11 700. Watch out: ratus means hundreds, not thousands; treating it as ribu makes the answer far too small.

单位相同 = unit yang sama 两个数都用 ribu 做单位时，可以先把前面的数字相减，再把单位 ribu 放回去，最后写成完整的数（补三个 0）。 例子：60 ratus − 15 ratus = 45 ratus = 4 500。 注意：只写出前面数字的差是不完整的，要记得换回完整的数。

the same unit = unit yang sama When both numbers are in ribu, subtract the digits in front first, put the unit ribu back, and write the full number with three zeros. Example: 60 ratus − 15 ratus = 45 ratus = 4 500. Watch out: the difference of the front digits alone is not complete; change it back into the full number.

两个单位 = dua unit 每个数都由两部分组成，例如“几 ribu 几 ratus”或“几 ribu 几 puluh”。先把两部分各自换成数字再加起来，得到一个普通的数；两个数都换好以后，再用竖式相减。 例子：7 ribu 5 ratus = 7 000 + 500 = 7 500；3 ribu 21 puluh = 3 000 + 210 = 3 210；7 500 − 3 210 = 4 290。 注意：几十个 puluh 会超过一百，要放到百位和十位；换算时每部分都要补对 0 的个数。

two units = dua unit Each number has two parts, such as ribu with ratus or ribu with puluh. Change each part into digits and add them to get an ordinary number, then subtract in columns. Example: 7 ribu 5 ratus = 7 500 and 3 ribu 21 puluh = 3 210, so 7 500 − 3 210 = 4 290. Watch out: tens of puluh are more than a hundred and reach the hundreds place, so add the right number of zeros to every part.