Subtraction of numbers within 10 000 10

### 1.1. Knowledge to remember

**8652 – 3917 = ?**

\(\begin{array}{l}

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

{8652}\\

{3917}

\end{array}} \\

\,\,\,\,\,\,4735

\end{array}\)

8652 – 3917 = …

- 2 cannot subtract 7, take 12 minus 7 equals 5, write 5 remember 1.
- 1 plus 1 equals 2; 5 minus 2 equals 3, write 3.
- 6 does not subtract 9, take 16 minus 9 equals 7, write 7 remember 1.
- 3 plus 1 equals 4; 8 minus 4 equals 4, write 4.

### 1.2. Solving Textbook Exercises

**Lesson 1:** Calculate

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

{6385}\\

{2927}

\end{array}} \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\underline { – \begin{array}{*{20}{c}}

{7563}\\

{4908}

\end{array}} \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\underline { – \begin{array}{*{20}{c}}

{8090}\\

{7131}

\end{array}} \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\underline { – \begin{array}{*{20}{c}}

{3561}\\

{\,\,\,924}

\end{array}} \)

**Solution guide:**

Perform subtraction of numbers in the same row from right to left.

\(\begin{array}{l}

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

{6385}\\

{2927}

\end{array}} \\

\,\,\,\,\,\,3458

\end{array}\) \(\begin{array}{l}

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

{7563}\\

{4908}

\end{array}} \\

\,\,\,\,\,\,2655

\end{array}\) \(\begin{array}{l}

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

{8090}\\

{7131}

\end{array}} \\

\,\,\,\,\,\,\,\,959

\end{array}\) \(\begin{array}{l}

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

{3561}\\

{\,\,\,924}

\end{array}} \\

\,\,\,\,\,\,2637

\end{array}\)

**Lesson 2:** Calculate then calculate

a) 5482 – 1956 b) 9996 – 6669

8695 – 2772 2340 – 512

__Solution guide:__

- Set calculation: Write calculations with numbers in the same row and column together.
- Calculation: Perform subtraction of numbers in the same row from right to left.

a)

\(\begin{array}{l}

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

{5482}\\

{1956}

\end{array}} \\

\,\,\,\,\,\,3526

\end{array}\) \(\begin{array}{l}

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

{8695}\\

{2772}

\end{array}} \\

\,\,\,\,\,\,5923

\end{array}\)

b)

\(\begin{array}{l}

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

{9996}\\

{6669}

\end{array}} \\

\,\,\,\,\,\,3327

\end{array}\) \(\begin{array}{l}

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

{2340}\\

{\,\,\,512}

\end{array}} \\

\,\,\,\,\,\,1828

\end{array}\)

**Lesson 3:** A shop has 4283m of fabric, has sold 1635m of fabric. How many meters of fabric are left in the store?

__Solution guide:__

*Summary:*

Yes : 4283m

Sold : 1635m

Also: … m?

To find the number of meters of fabric left in the shop, we subtract the number of meters of fabric sold at the beginning.

*Solution*

The store has the remaining number of meters of fabric:

4283 – 1635 = 2648(m)

Answer: 2648 m.

**Lesson 4: **Draw a line segment AB with length 8cm and then determine the midpoint O of that line.

__Solution guide:__

- Draw line segment AB.
- Locate the midpoint O of the line segment AB.
- Note: O lies on line segment AB and divides that line into two equal parts.

Follow these steps:

- Draw line segment AB 8 cm long (with a ruler)
- Mental division: 8cm : 2 = 4cm
- Set the 0cm line of the ruler to coincide with point A, the edge of the ruler to coincide with line segment AB, point O on line segment AB so that O corresponds to the 4cm line of the ruler.

.

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