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• multiplication of decimals (up to 2 decimal places) by a 1-digit whole number
What will we learn today?
Decimals Multiplication
In the previous lectures, we have learnt about
addition and subtraction in decimals.
Let’s recap!
Applying what we have learnt
Try this out!
Mr Li used 2.5kg of rice on Monday and 1.75 kg on Tuesday. He used a total of 9 kg Monday and Wednesday. How much rice did he use on
Wednesday?
Solution
Mr Li used 2.5kg of rice on Monday and 1.75 kg more on Tuesday. He used a total of 9 kg from Monday to Wednesday.
How much rice did he use on Wednesday?
Step 1: 2.5kg + 1.75kg =___kg
Solution
Mr Li used 2.5kg of rice on Monday and 1.75 kg more on Tuesday. He used a total of 9 kg from Monday to Wednesday.
How much rice did he use on Wednesday?
2.50
+ 1.75
Step 1: 2.5kg + 1.75kg = 4.25kg
He used 4.25kg of rice on Tuesday.
Solution
Mr Li used 2.5kg of rice on Monday and 1.75 kg more on Tuesday. He used a total of 9 kg from Monday to Wednesday.
How much rice did he use on Wednesday?
2.50
+ 4.25
Step 2: 2.5kg + 4.25kg = 6.75kg
He used 6.75kg of rice on Monday and Tuesday.
Solution
Mr Li used 2.5kg of rice on Monday and 1.75 kg more on Tuesday. He used a total of 9 kg from Monday to Wednesday.
How much rice did he use on Wednesday?
9.00
- 6.75
Step 3: 9.00 kg - 6.75kg = 2.25 kg
He used 2.25kg of rice on Wednesday.
Multiplication in decimals
Try this out!
1. The length of ribbon A is 10.08 m.
Ribbon B is 3 times as long as ribbon A.
Find the length of ribbon B.
Try this out!
1. The length of ribbon A is 10.08 m.
Ribbon B is 3 times as long as ribbon A.
Find the length of ribbon B.
Let’s draw models to help us visualize the scenario.
Try this out!
1. The length of ribbon A is 10.08 m.
Ribbon B is 3 times as long as ribbon A.
Find the length of ribbon B.
A
10.08m
Try this out!
1. The length of ribbon A is 10.08 m.
Ribbon B is 3 times as long as ribbon A.
Find the length of ribbon B.
A
10.08m
B
Try this out!
1. The length of ribbon A is 10.08 m.
Ribbon B is 3 times as long as ribbon A.
Find the length of ribbon B.
A
10.08m
B
?
Try this out!
1. The length of ribbon A is 10.08 m.
Ribbon B is 3 times as long as ribbon A.
Find the length of ribbon B.
10.08 x 3 =_____m
A
10.08m
B
?
Do multiplication workings accordingly
10.08
x 3
Do multiplication workings accordingly
10.08
x 3
4
+2
Do multiplication workings accordingly
10.08
x 3
24
+2
Do multiplication workings accordingly
10.08
x 3
.24
Place the decimal place in a straight line.
Do multiplication workings accordingly
10.08
x 3
0.24
Do multiplication workings accordingly
10.08
x 3
30.24
Try this out!
1. The length of ribbon A is 10.08 m.
Ribbon B is 3 times as long as ribbon A.
Find the length of ribbon B.
10.08 x 3 =30.24m
A
10.08m
B
30.24m
Are you ready to try out the questions?
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