Unit 13
Tolak Perpuluhan
Sebuah bakul ada 15.3 kg manggis. 4.8 kg dijual.
Berapakah jisim manggis yang tinggal?

小数减法 = tolak perpuluhan
从原有的重量里减去卖掉的重量,要用减法。小数减法也要把小数点对齐,从最右边一位减起,不够减就向左边借一。这个单元学到三位小数的减法,包括连续减两个数。
例子:5.8 − 2.3 = 3.5。
注意:答案的小数点也要对齐。
subtracting decimals = tolak perpuluhan
Taking the amount sold away from the starting mass needs subtraction. With decimals, line up the decimal points, subtract from the rightmost place, and borrow from the left when a digit is too small. In this unit we subtract decimals with up to three places, including taking away two numbers in a row.
Example: 5.8 − 2.3 = 3.5.
Watch out: line up the decimal point in the answer too.
Cara 1
Susun titik perpuluhan selajur
15.3 − 4.8
| 1 | 5 | . | 3 | |
| − | 4 | . | 8 | |
| 1 | 0 | . | 5 |
3 − 8 ✘ → kumpul semula: 13 − 8 = 5
竖式减法 = tolak bentuk lazim
小数点对齐以后,从十分位减起:三不够减八,要向个位借一,一个一等于十个零点一,所以变成十三减八得五;个位五借走一变四,四减四得零;十位一。答案 10.5 公斤。
例子:7.2 − 3.6 = 3.6。
注意:借位以后,那一位要少一。
column subtraction = tolak bentuk lazim
With the points lined up, start at the tenths: 3 is less than 8, so borrow 1 from the ones; one whole is ten tenths, so it becomes 13 − 8 = 5. The ones digit 5 becomes 4, and 4 − 4 = 0; the tens digit is 1. The answer is 10.5 kg.
Example: 7.2 − 3.6 = 3.6.
Watch out: after borrowing, that place is 1 less.
Cara 2
Lompat ke belakang pada garis nombor
9.2 − 1.5
7.0
7.7
8.0
8.2
9.0
9.2
mula
▼
▼
tamat
▼
▼
9.2 − 1 − 0.5 = 7.7
数线往回跳 = lompat ke belakang
减一点五可以分成两步:先减一,从九点二跳到八点二;再减零点五,往回跳五小格,从八点二到七点七。减法在数线上就是往左边走。
例子:6.3 − 1.4 → 6.3 − 1 = 5.3,再 − 0.4 = 4.9。
注意:跨过整数八的时候,八点零的前一格是七点九。
jump backwards on the number line = lompat ke belakang
Taking away 1.5 can be done in two steps: take 1 to go from 9.2 to 8.2, then take 0.5 by jumping back 5 small steps to 7.7. Subtraction moves to the left on the number line.
Example: 6.3 − 1.4: 6.3 − 1 = 5.3, then − 0.4 = 4.9.
Watch out: when passing 8, the step before 8.0 is 7.9.
Tempat kosong
Tulis sifar sebelum menolak
2.5 − 0.36
补 0 再减 = tulis sifar dahulu
被减数 2.5 只有一位小数,减数 0.36 有两位。先在 2.5 后面补 0 写成 2.50,百分位才有数可以减。零不够减六,向十分位借一,得十减六等于四;十分位五借走一变四,四减三得一。答案 2.14。
例子:4.2 − 1.15 = 4.20 − 1.15 = 3.05。
注意:不补 0 很容易把 6 直接写下来,这是错的。
write a zero first = tulis sifar dahulu
2.5 has one decimal place and 0.36 has two. Write 2.5 as 2.50 so the hundredths place has a digit. 0 is less than 6, so borrow from the tenths: 10 − 6 = 4; the tenths 5 becomes 4, and 4 − 3 = 1. The answer is 2.14.
Example: 4.2 − 1.15 = 4.20 − 1.15 = 3.05.
Watch out: without the zero it is easy to copy the 6 down, which is wrong.
Cari kesilapan
Nombor bulat ditolak daripada perpuluhan
6.254 − 2
✘ Salah
| 6 | . | 2 | 5 | 4 | |
| − | 2 | ||||
| 6 | . | 2 | 5 | 2 |
✔ Betul
| 6 | . | 2 | 5 | 4 | |
| − | 2 | . | 0 | 0 | 0 |
| 4 | . | 2 | 5 | 4 |
找错 = cari kesilapan
整数 2 是两个一,它的小数点在 2 的后面,所以 2 要写在个位 6 的下面,而不是写在最右边。错误的写法把 2 当成 0.002 来减,得到 6.252。正确答案是 4.254。
例子:3.75 − 1 = 2.75。
注意:整数减小数或小数减整数,都要先对齐小数点。
find the mistake = cari kesilapan
The whole number 2 means two ones; its decimal point is after the 2, so the 2 goes under the ones digit 6, not at the far right. The wrong working treats 2 as 0.002 and gets 6.252. The correct answer is 4.254.
Example: 3.75 − 1 = 2.75.
Watch out: always line up the decimal points first.
Nombor bulat tolak dua perpuluhan
Tolak dari kiri ke kanan
8 − 0.75 − 3.108
Langkah 1
| 8 | . | 0 | 0 | |
| − | 0 | . | 7 | 5 |
| 7 | . | 2 | 5 |
Langkah 2
| 7 | . | 2 | 5 | 0 | |
| − | 3 | . | 1 | 0 | 8 |
| 4 | . | 1 | 4 | 2 |
整数连减 = nombor bulat tolak berturut-turut
先把八写成 8.00,减 0.75 得 7.25;再把 7.25 写成 7.250,减 3.108 得 4.142。每一步都补零、对齐小数点,从右边减起。
例子:5 − 0.5 − 1.25 = 4.5 − 1.25 = 3.25。
注意:整数后面补零时,要补到和另一个数一样多的小数位。
a whole number minus two decimals = nombor bulat tolak berturut-turut
Write 8 as 8.00 and take away 0.75 to get 7.25; then write 7.25 as 7.250 and take away 3.108 to get 4.142. At each step fill in zeros, line up the points and subtract from the right.
Example: 5 − 0.5 − 1.25 = 4.5 − 1.25 = 3.25.
Watch out: add enough zeros to match the other number's decimal places.
Tolak berturut-turut
Dua perpuluhan ditolak
43.6 − 15.27 − 0.853
Langkah 1
| 4 | 3 | . | 6 | 0 | |
| − | 1 | 5 | . | 2 | 7 |
| 2 | 8 | . | 3 | 3 |
Langkah 2
| 2 | 8 | . | 3 | 3 | 0 | |
| − | 0 | . | 8 | 5 | 3 | |
| 2 | 7 | . | 4 | 7 | 7 |
小数连减 = tolak perpuluhan berturut-turut
按从左到右的次序:先把四十三点六写成四十三点六零,减去十五点二七,得二十八点三三;再补零写成二十八点三三零,减去零点八五三,得二十七点四七七。也可以先把两个要减的数加起来,再从原来的数一次减掉,答案一样。
例子:10.5 − 2.25 − 3.1 = 5.15。
注意:连续借位时,每一位都要记得少一。
subtract two decimals in a row = tolak perpuluhan berturut-turut
From left to right: 43.60 − 15.27 = 28.33, then 28.330 − 0.853 = 27.477. You can also add the two numbers taken away first: 15.27 + 0.853 = 16.123, then 43.6 − 16.123 gives the same answer.
Example: 10.5 − 2.25 − 3.1 = 5.15.
Watch out: when borrowing across several places, each place goes down by 1.
Nombor yang ditolak
23.5 − □ = 8.64
Nombor yang ditolak = nombor asal − jawapan
Tolak
| 2 | 3 | . | 5 | 0 | |
| − | 8 | . | 6 | 4 | |
| 1 | 4 | . | 8 | 6 |
Semak
| 2 | 3 | . | 5 | 0 | |
| − | 1 | 4 | . | 8 | 6 |
| 8 | . | 6 | 4 |
求减数 = cari nombor yang ditolak
原来的数是二十三点五,减去某个数以后剩八点六四。被减去的数等于原来的数减去剩下的数,先补零写成二十三点五零,再减八点六四,得十四点八六。最后用原来的数减去十四点八六检查,刚好剩八点六四。
例子:9 − □ = 4.5 → □ = 4.5。
注意:被减去的数要用减法求,不是加法。
find the number taken away = cari nombor yang ditolak
The starting number is 23.5 and 8.64 is left, so the number taken away is 23.50 − 8.64 = 14.86. Check: 23.50 − 14.86 = 8.64.
Example: 9 − □ = 4.5, so □ = 4.5.
Watch out: the number taken away is found by subtracting, not adding.
Semak cepat
7.05 − 2.8 = ?
补 0 与借位 = sifar dan kumpul semula
两个数的小数位数不同,先在较短的数后面补 0,让小数点和每一位都对齐;从百分位开始减,不够减就向左边一位借 1(借来的 1 等于右边一位的 10)。
例子:6.04 − 1.7 = 6.04 − 1.70 → 十分位 0 不够减 7,借 1 得 10 − 7 = 3,个位 6 − 1 − 1 = 4 → 4.34。
注意:一位小数的数字在十分位,要写在十分位下面,不能对着百分位写。
zeros and borrowing = sifar dan kumpul semula
The numbers have different numbers of decimal places, so put a zero after the shorter one to line up every place. Subtract from the hundredths, borrowing 1 from the place on the left when a digit is too small (that 1 is worth 10 in the place on the right).
Example: 6.04 − 1.7 = 6.04 − 1.70: tenths 0 is less than 7, so borrow, 10 − 7 = 3; ones 6 − 1 − 1 = 4, giving 4.34.
Watch out: the digit of a one-place decimal belongs in the tenths, not under the hundredths.
Tolak daripada 10
10 − 3.456 = ?
从整数减 = tolak daripada nombor bulat
整数后面补上小数点和三个 0,和减数的小数位数一样。右边几位都是 0,不够减,要从个位开始一路借过来:中间几位借了又被借走,都变成 9,最右边一位变成 10。
例子:5 − 1.25 = 5.00 − 1.25:借位后变成 4、9、10 → 3.75。
注意:小数部分也要减,不能只把整数部分相减;借位后中间的 0 会变成 9。
subtract from a whole number = tolak daripada nombor bulat
Give the whole number a decimal point and three zeros to match the other number. The zeros on the right are too small, so borrow all the way from the ones: the middle places become 9 and the last place becomes 10.
Example: 5 − 1.25 = 5.00 − 1.25: after borrowing the digits are 4, 9, 10, giving 3.75.
Watch out: subtract the decimal part too, not just the whole numbers; after borrowing, the middle zeros become 9.
Ringkasan
Syabas!
. selajur
Susun titik perpuluhan, tulis sifar di tempat kosong, dan kumpul semula jika perlu.
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