Decimals

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Decimals
Revision Level E
Add Subtract Decimals
Multiplying by 2 Simple Decimals
Dividing 2 Simple Decimals
Rounding to Any Number of Decimal Places
Rounding to Significant Figures
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Profit and Loss
Hire Purchase
Salaries Overtime
Foreign Exchange
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Starter Questions
If a 7 b 4 and c 10 Write down as many
equations as you can
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e.g. a b 11
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Decimals
Revision of Level E
Learning Intention
Success Criteria

1. Understand how to round to 1 decimal place.

1. To revise Level E work.
2. Apply rules for multiplying and dividing by
10, 100 and 1000.
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Decimals
Revision Level E
MNU 3-03a
6 hundredths
1. What does 6 stand for in 0.26 ?
2. What number lies halfway between 0.1 and 0.02 ?
0.06
3. Round to 1 decimal place 34.75
34.8
Shop A 80p Shop B 79p B is cheaper!
4. Calculate 4.76 x 100
476
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5. Calculate 567.89 1000
0.56789
6. Shop A sell 20 CDs for 16 and Shop B sells
40 CDs for 31.60. Which shop is the cheapest.
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Decimals
Revision Level E
MNU 3-03a
Now try Exercise 1 Ch13 (page 56)
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Starter Questions

• Two numbers add to give 12 and divide to give 3.
  Find the two numbers.
• 2. Two numbers subtract to give 5 and
• multiply to 24. Find the two numbers.
• 3. Make your own question up.

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Decimals
Addition Subtraction
Learning Intention
Success Criteria

1. Remember to keep decimal point in line.

1. We are learning to add and subtract decimal
numbers.
2. Make use of trailing 0s when needed.
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Decimals
Addition Subtraction
MNU 3-03a
Example 3.2 0.487 5.73
Keep point in line
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Decimals
Addition Subtraction
MNU 3-03a
Example 6.2 3.19 1.783
Add first
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Then subtract
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Decimals
Addition Subtraction
MNU 3-03a
Now try Exercise 2 Ch13 (page 58)
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Starter Questions
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Decimals
Simple Multiplication
Learning Intention
Success Criteria
1. Apply rules to do simple multiplication.
1. We are learning to do simple decimal
multiplication.
2. Show clear working.
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Decimals
Simple Multiplication
MNU 3-03a
0. 24
6 x 4 24
Example 1 0.6 x 0.4
2 digits after decimal place
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0. 027
9 x 3 27
Example 2 0.09 x 0.3
3 digits after decimal place
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Decimals
Simple Multiplication
MNU 3-03a
0. 0355
71 x 5 355
Example 3 0.071 x 0.5
4 digits after decimal place
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Decimals
Simple Multiplication
MNU 3-03a
Now try Exercise 5 Ch13 (page 62)
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Starter Questions
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Decimals
Division of a Decimal
Learning Intention
Success Criteria
1. Understand simple rule for dividing decimals.
1. We are learning to divide simple decimal
numbers.
2. Apply them to simple calculations.
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Decimals
Division of a Decimal
MNU 3-03a
Do not attempt to divide by a decimal, multiply
the divisor so it is a whole number first.
Example 1 3.5 0.7
35 7
5
x 10
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x 10
Example 2 0.8 0.2
8 2
4
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Decimals
Division of a Decimal
MNU 3-03a
Do not attempt to divide by a decimal, multiply
the divisor so it is a whole number first.
Example 3 0.036 0.04
3.6 4
0.9
x 100
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Example 4 24 3000
24 31000
0.008
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Decimals
Division of a Decimal
MNU 3-03a
Now try Exercise 6 Ch13 (page 63)
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Starter Questions
The answer to the question is 60
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Write down as many questions as you can
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Decimals
Rounding to Any Number of Decimal Places
Learning Intention
Success Criteria
1. Use previous knowledge to help round to any
number of decimal places.
1. We are learning to round to any number of
decimal places.
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Decimals
Rounding to Any Number of Decimal Places
MNU 3-03a
When rounding to
1 decimal place look at 2nd decimal figure
e.g. 2.46
e.g. 6.456
2 decimal place look at 3rd decimal figure
e.g. 3.7846
3 decimal place look at 4th decimal figure
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e.g. 13.1146
4 decimal place look at 5th decimal figure
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Decimals
Rounding to Any Number of Decimal Places
MNU 3-03a
Example The number 4.2615937
Rounded to 1 decimal place, the number is
4.3
4.26
Rounded to 2 decimal place, the number is
4.262
Rounded to 3 decimal place, the number is
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4.2616
Rounded to 4 decimal place, the number is
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Decimals
Rounding to Any Number of Decimal Places
MNU 3-03a
Now try Exercise 7 Ch13 (page 64)
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Starter Questions
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Significant Numbers
Learning Intention
Success Criteria

1. Understand what the term significant figure means.

1. We are learning about the term significant
   figure.

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1. Apply knowledge to problems.

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Significant Numbers
MNU 3-03a

• In mathematics a figure or digit is significant
• if it gives an idea of both
• Quantity
• Accuracy

IMPORTANT If zeros are employed just to
position the decimal point then they are
considered NOT significant.
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e.g.
Has 3 significant figures.
Has 3 significant figures.
Has 3 significant figures.
Has 3 significant figures.
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Significant Numbers
MNU 3-03a
IMPORTANT When dealing with WHOLE NUMBERS you
need More information before you can tell if
trailing zeros are significant.
Is it 2 or 3 !!!
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If I said there are 360 deg. in a circle. How
many significant figures.
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2
If I said 359 to the nearest ten is 360. How many
significant figures.
YOU NEED TO KNOW THE CONTEXT OF THE QUESTION
WHEN DEALING WITH WHOLE NUMBERS WITH TRAILING
ZEROS.
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WORK OUT WHAT THE ZERO MEANS
Significant Figures
Decimals 0.001090
MNU 3-03a
To the left of The number
Middle of the number
To the right of the number
Not Significant
Always Significant
Always Significant
Whole Numbers 03060
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To the left of The number
Middle of the number
? Depends More Info.
Read Question
Not Significant
Always Significant
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Significant Numbers
MNU 3-03a
Now try Ex 8 Ch13 (page 65)
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Starter Questions
Q1. 0.5 5 x 8
Q2. Multiply out the brackets
Q3.
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Q4.
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Profit and Loss
Learning Intention
Success Criteria

1. Understand the terms PROFIT and LOSS.

• We are learning the
• terms profit and loss.

1. Apply knowledge to calculations. In context.

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Profit and Loss
Profit When you sell something for MORE
than you bought it.
PROFIT Selling Price Buying Price
Loss When you sell something for LESS than
you bought it.
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LOSS Buying Price Selling Price
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Profit and Loss
Example 1 If I buy a Playstation for 100 and
sell it for 120.
120-100 20
I have made a PROFIT of
Example 2 I bought a bunch of flowers for 5.50
and tried to sell them for a profit. But I found
it difficult to sell them. I sold them for 4.00
before they went off.
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I made a LOSS of
5.50 - 4.00 1.50
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Profit and Loss
MNU 3-03a
Now try Ex 9 Ch13 (page 67) Q1 Q3
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Hire Purchase
Learning Intention
Success Criteria

1. To know the meaning of the term HIRE PURCHASE.

• We are learning the
• the meaning of the term Hire Purchase.

1. Apply the process of working out the Hire
   Purchase for everyday products.

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Starter Questions
MNU 3-03a
Q1. Expand out 2j (k 5g 4jk)
Q2. Find all the missing angles
25o
Q3.
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Q4.
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Hire Purchase
Hire Purchase When you pay for goods
by putting down a deposit and then paying
the rest up in small fixed payments over a
period of time.
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Normally you pay more for the goods using this
method.
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Hire Purchase
Buying Products Hoover Cash Price 365.50 or
by H.P. 75 deposit 12 Payment 28.80
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How much more do you pay by using Hire Purchase
75 12 x 28.80 420.60
Total H.P. price
Difference in price
420.60 - 365.50 55.10
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Hire Purchase
MNU 3-03a
Now try Ex 9 Ch13 (page 68) Q4 Q7
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Starter Questions
Q1. Expand out 2a (a c 4ab)
Q2. Find the missing angle
22o
Q3.
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Q4.
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Salaries Overtime
Learning Intention
Success Criteria

1. To know the meaning of the terms Salary and
   Overtime.

1. We are learning to calculate Salaries and
   Overtime.

1. Apply knowledge to calculations. In context.

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Salaries Overtime
Salary How much a person is paid to do a
job. Can be measured weekly, monthly
or annually.
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Overtime Extra work outside normal work
time. Usually at night or weekends.
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Salaries Overtime
Example 1 Mick the mechanic gets paid
1725.20 a month. How much is his annual salary.
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1725.20 x 12 20 702.40
Annual Salary is
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Salaries Overtime
Example 2 Claire the clerkess gets an annual
salary of 19 003.40. How much is her weekly wage.
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19 003.40 52 365.45
Weekly Salary is
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Salaries Overtime
Example 3 Percy works for 12.90 per hour.
His overtime rate is time a half. What does
he get paid for 4 hours overtime.
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4 x 12.90 x 1.5 77.40
4 hours Overtime is
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Salaries Overtime
Level F
Now try Ex 9 Ch13 (page 68) Q8 Q14
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Starter Questions
Q1. Expand out 2a (a c 4ab)
Q2. Find two missing angles
32o
Q3. Find y
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Q4. The answer is 45. What is the queston.
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Foreign Exchange
Learning Intention
Success Criteria
1. Understand the term exchange rate and be apply
it to convert s to another currency.

1. We are learning to convert s to another
   currency and vice versa.

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1. Be able to convert back to s.

3. Show clear working.
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Foreign Exchange
Think going on holiday !
The currency in most of Europe is the euro
The exchange rate is approximately
1 ? 1.54
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Converting s to Euros simply multiply
(a) To change 80 to euros
80 x 1.54
123.20
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Foreign Exchange
Coming back from holiday we want to do the
opposite i.e. euros to s
Think back from holiday !
The exchange rate is approximately
1 ? 1.54
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Converting Euros s to s simply divide
To change 616 to s
616 1.54
400
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Foreign Exchange
MNU 3-03a
Now try Ex 9 Ch13 (page 70) Q15 Q20
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