Subtract three-digit numbers (remember once)

### 1.1. Calculation

**a) 432 – 215 = ?**

\(\frac{{ – \begin{array}{*{20}{c}}

{432}\\

{215}

\end{array}}}{{\,\,\,217}}\)

- 2 cannot subtract 5, take 12 minus 5 equals 7, write 7 remember 1.
- 1 plus 1 equals 2, 3 minus 2 equals 1, write 1
- 4 minus 2 equals 2, write 2

**b) 627 – 143 = ?**

\(\frac{{ – \begin{array}{*{20}{c}}

{627}\\

{143}

\end{array}}}{{\,\,\,484}}\)

- 7 minus 3 equals 4, write 4
- 2 cannot subtract 4, take 12 minus 4 equals 8, write 8 remember 1.
- 1 plus 1 equals 2, 6 minus 2 equals 4, write 4

### 1.2. Solving Textbook Exercises

**Lesson 1:** Calculate

\(\underline { – \begin{array}{*{20}{c}}

{541}\\

{127}

\end{array}} \) \(\underline { – \begin{array}{*{20}{c}}

{422}\\

{114}

\end{array}} \) \(\underline { – \begin{array}{*{20}{c}}

{564}\\

{215}

\end{array}} \) \(\underline { – \begin{array}{*{20}{c}}

{783}\\

{356}

\end{array}} \) \(\underline { – \begin{array}{*{20}{c}}

{694}\\

{237}

\end{array}} \)

**Solution guide:**

\({\frac{{ – \begin{array}{*{20}{c}}

{541}\\

{127}

\end{array}}}{{\,\,\,414}}}\) \({\frac{{ – \begin{array}{*{20}{c}}

{422}\\

{114}

\end{array}}}{{\,\,\,308}}}\) \({\frac{{ – \begin{array}{*{20}{c}}

{564}\\

{215}

\end{array}}}{{\,\,\,349}}}\) \({\frac{{ – \begin{array}{*{20}{c}}

{783}\\

{356}

\end{array}}}{{\,\,\,527}}}\) \({\frac{{ – \begin{array}{*{20}{c}}

{694}\\

{237}

\end{array}}}{{\,\,\,457}}}\)

__ Note:__ Borrowing the next row value of the subtracted number, you must remember to subtract or subtract the next row value of the subtracted number before subtracting.

**Lesson 2:** Calculate

\(\underline { – \begin{array}{*{20}{c}}

{627}\\

{443}

\end{array}} \) \(\underline { – \begin{array}{*{20}{c}}

{746}\\

{251}

\end{array}} \) \(\underline { – \begin{array}{*{20}{c}}

{516}\\

{342}

\end{array}} \) \(\underline { – \begin{array}{*{20}{c}}

{935}\\

{551}

\end{array}} \) \(\underline { – \begin{array}{*{20}{c}}

{555}\\

{160}

\end{array}} \)

**Solution guide:**

\(\frac{{ – \begin{array}{*{20}{c}}

{627}\\

{443}

\end{array}}}{{\,\,\,184}}\) \({\frac{{ – \begin{array}{*{20}{c}}

{746}\\

{251}

\end{array}}}{{\,\,\,495}}}\) \({\frac{{ – \begin{array}{*{20}{c}}

{516}\\

{342}

\end{array}}}{{\,\,\,174}}}\) \({\frac{{ – \begin{array}{*{20}{c}}

{935}\\

{551}

\end{array}}}{{\,\,\,384}}}\) \({\frac{{ – \begin{array}{*{20}{c}}

{555}\\

{160}

\end{array}}}{{\,\,\,395}}}\)

__ Note:__ Borrowing the next row value of the subtracted number, you must remember to subtract or subtract the next row value of the subtracted number before subtracting.

**Lesson 3:** Friend Binh and friend Hoa collected everything

stamps, in which Binh’s friend collected

$128$stamp. How many stamps did Hoa collect?

**Solution guide:**

- The number of stamps Hoa collects is equal to the number of stamps you both collect minus the number of stamps Collected Vase
- Summary:

Collectible vases and flowers:

$335$stamp

Collection jar:

$128$stamp

Collected flowers: … ? stamp

**Solution**

Hoa collected the number of stamps as:

(stamp)

Answer:

$207$stamp

**Lesson 4:** Solve the problem according to the following summary:

Long string:

$243$cm

Cut away:

$27$cm

Rest : … ? cm

**Solution guide:**

- The remaining string is equal to the length of the string minus the length of the cut.

**Solution**

The remaining string is long:

(cm)

Answer:

cm.

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