8 . multiplication table

Lesson 1: Mental arithmetic

a) 8 x 1 = 8 x 5 = 8 x 0 = 8 x 8 =

8 x 2 = 8 x 4 = 8 x 6 = 8 x 9 =

8 x 3 = 8 x 7 = 8 x 10 = 0 x 8 =

b) 8 x 2 = 8 x 4 = 8 x 6 = 8 x 7 =

2 x 8 = 4 x 8 = 6 x 8 = 7 x 8 =

__Solution guide:__

Mentally multiply the multiplications in the multiplication table by 8 and then fill in the blanks with the results.

a) 8 x 1 = 8 8 x 5 = 40 8 x 0 = 0 8 x 8 = 64

8 x 2 = 16 8 x 4 = 32 8 x 6 = 48 8 x 9 =72

8 x 3 = 24 8 x 7 = 56 8 x 10 = 80 0 x 8 = 0

b) 8 x 2 = 16 8 x 4 = 32 8 x 6 = 48 8 x 7 = 56

2 x 8 = 16 4 x 8 = 32 6 x 8 = 48 7 x 8 = 56

(Remark: In multiplication, when changing the positions of the factors, the product does not change).

Lesson 2: Calculate

a) 8 x 3 + 8 b) 8 x 8 + 8

8 x 4 + 8 8 x 9 + 8

__Solution guide:__

- Find the value of the multiplication.
- Take the result you just found plus the remaining number.

a) 8 x 3 + 8 = 24 + 8 = 32

8 x 4 + 8 = 32 + 8 = 40

b) 8 x 8 + 8 = 64 + 8 = 72

8 x 9 + 8 = 72 + 8 = 80.

Lesson 3: From a 50 m long electric coil, 4 segments are cut, each 8 m long. How many meters are left in that coil?

__Solution guide:__

*Summary:*

Initial : 50 m

Cut 4 segments, each 8m

Remaining : … m ?

- Calculate the length of the cut string by multiplying 8 times 4.
- Take the original length of the coil minus the length of the cut you just found.

*Solution:*

The number of meters of wire cut is:

8 x 4 = 32 (m)

The number of meters left on that coil is:

50 – 32 = 18 (m)

Answer: 18 m.

Lesson 4: Write the correct multiplication in the dot?

a) There are 3 rows, each row has 8 squares. Number of squares in rectangle ABCD is :……………………= 24 (squares)

b) There are 8 columns, each column has 3 squares. Number of squares in rectangle ABCD is:……………= 24 (squares)

Comments: ……………………=……………………. …….

__Solution guide:__

An operation involving n identical terms and all of which is a is written as a multiplication as ax n.

*Solution:*

There are 3 rows, each row has 8 squares. The number of squares in rectangle ABCD is:

8 x 3 = 24 (squares)

There are 8 columns, each column has 3 squares. The number of squares in rectangle ABCD is :

3 x 8 = 24 (squares)

Comment: 8 x 3 = 3 x 8

(When the two factors of multiplication are swapped, the product does not change.)

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