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Mathematics Then and NowPowerPoint Presentation

Mathematics Then and Now

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### MathematicsThen and Now

Most notable advancements in the early development of mathematics:

- Mayans
- Babylonians
- Egyptians
- Greeks
- Chinese

Wrote on tablets mathematics:

- Used two symbols for numbers
- Ones
- Tens

- Used a base 60 place system
- clocks (60 seconds, 60 minutes or
3600 seconds)

- circle (360°)

- clocks (60 seconds, 60 minutes or

Tablet with numbers mathematics:

Babylonians1 set of 3600 mathematics:

52 sets of 60

30 sets of 1

1

52

30

- 1 ˟ 3600 = 3600
- 52 ˟ 60 = 3120
- 30 ˟ 1 = 30
- 6750

Babylonian multiplication concentrated on perfect squares mathematics:

(3)(4) = (3 + 4)2 – 32 – 42 = 49 – 9 – 16 = 24 = 12

2 2 2

Babylonian MultiplicationSimple grouping system (hieroglyphics) mathematics:

The Egyptians used the

stickfor 1

heel bone for 10

scrollfor 100

lotus flower for 1,000

bent finger for 10,000

burbot fishfor 100,000

astonished man

for 1,000,000.

Egyptian Mathematics3000 + 200 + 40 + 4 mathematics:

= 3244

What are the following values?

52

21,238

Egyptian MathematicsThe Ancient Egyptians used a pencil and paper method for multiplication which was based on doubling and addition.

Egyptian MultiplicationWrite multiplication which was based on doubling and addition.down 1 and 50

1 50

Work down, doubling the numbers, so that you’ve now got 2, 4, 8, 16, etc. lots of 53.

2 100

4 200

Stop when the number of the left (16) is more than half of the other number you are multiplying (18).

8 400

16 800

Look for numbers on the left that add up to 18 (2 and 16).

18 x 50900

Cross out the other rows of numbers.

Add up the remaining numbers on the right to get the final answer.

Write 1 and 76, meaning 1 lot of 76. multiplication which was based on doubling and addition.

1 76

Work down, doubling the numbers, so that you’ve now got 2, 4, 8, 16, etc. lots of 76.

2 152

4 304

Stop when the number of the left (32) is more than half of the other number you are multiplying (39).

8 608

16 1216

Look for numbers on the left that add up to 39 (1, 2, 4 and 32).

39 x 7632 2432

Cross out the other rows of numbers.

2964

Add up the remaining numbers on the right to get the final answer.

This jar holds 17 multiplication which was based on doubling and addition.litres of water.How much water will 25 jars hold?

A potter makes 35 pots each month.

How many will he make in a year?

Now it’s your turn!This chariot travels 23km in an hour. How far will it travel in 6 hours?

This demonstrates that we can add, subtract, multiply, and divide numbers in multiple ways and still get the same answer

We have seen that different civilizations had different methods to handle basic arithmetic

Arithmetic4 divide numbers in multiple ways and still get the same answer3

+ 25

+ 8

Add the partial sums

(60 + 8)

Partial Sums

Add the tens (40 + 20)

60

Add the ones (3 + 5)

68

2 divide numbers in multiple ways and still get the same answer68

Add the hundreds (200 + 400)

+ 483

+ 11

Add the partial sums

(600 + 140 + 11)

Partial Sums

600

Add the tens (60 +80)

140

Add the ones (8 + 3)

751

Lattice Sums divide numbers in multiple ways and still get the same answer

7 8

+ 4 8

Create a grid

Draw diagonals

Add each column, placing the tens digit in the upper half of the cell and the ones digit in the bottom half of the cell

Add along each diagonal and record any regroupings in the next diagonal

1

1

1

6

1

2

6

The opposite change rule says that if a value is added to one of the numbers, then subtract the value from the other number

88

+ 36

90

+ 34

100

+ 24

+10

+2

- 2

- 10

Opposite Change124

Let’s look at some different methods to subtract numbers one of the numbers, then subtract the value from the other number

We are familiar with the basic borrowing methods, but did you know we can subtract by adding?

SubtractionCounting Up-Hill one of the numbers, then subtract the value from the other number

38 – 14 =

24

1. Place the smaller number at the bottom of the hill and the larger at the top.

30

38

+8

2. Start with 14, add to the next friendly number. (14+6=20)

+10

20

Record the numbers added at each interval:

(6+10+8=24)

3. Start with 20, add to the next friendly number. (20+10=30)

+6

14

4. Start with 30, add to get 38. (30+8=38)

75 one of the numbers, then subtract the value from the other number

+ 61

75

– 38

Replace each digit to be subtracted with its nines complement, and then add

Delete the leading 1

Add 1 to the final result

136

+1

Nines Complement37

Let’s look at some different methods to multiply numbers one of the numbers, then subtract the value from the other number

We have already seen two methods to multiply beyond our current procedure (Babylonian method of squares and the Egyptian method of doubles. Let’s look at a few more.

Multiplication+ one of the numbers, then subtract the value from the other number

2

7

(20+7)

When multiplying by “Partial Products,” you must first multiply parts of these numbers, then you add all of the results to find the answer.

X

6

4

(60+4)

1,200

Multiply 20 X 60 (tens by tens)

420

Multiply 60 X 7 (tens by ones)

80

Partial ProductMultiply 4 X 20 (ones by tens)

28

Multiply 7 X 4 (ones by ones)

Add the results

1,728

Lattice Product one of the numbers, then subtract the value from the other number

Create a grid

Draw diagonals

Copy one digit across top of grid and the other along the right side

Multiply each digit in the top factor by each digit in the side factor, placing the tens digit in the upper half of the cell and the ones digit in the bottom half of the cell

Add along each diagonal and record any regroupings in the next diagonal

1,175

25 x 47 =

2

5

2

0

4

8

0

1

1

3

1

7

4

5

1

7

5

We can often perform basic arithmetic in our head faster than we can by writing it down or plugging it into a calculator.

We need to recognize certain patterns to help the process.

Math TricksWe can add large set of numbers quickly by grouping values that add to ten

2

52

47

63

28

+ 16

10

10

20

10

10

26

Group Tens for Addition6

20

6

We can multiply by four simply by doubling the value twice: that add to ten

37 x 4

115 x 4

double

double

74

230

Multiply by Fourdouble again

double again

148

460

We can multiply by five simply by multiplying by ten and then take half:

42 x 5

73 x 5

multiply by 10

multiply by 10

420

730

Multiply by Fivetake half

take half

210

365

We can multiply by eleven by keeping the first and last digit and then adding digits that are next to each other to get the rest of the digits

3+5

1+4

4+2

8

5

5

2

35 x 11 =

3

142 x 11 =

1

6

Multiply by ElevenKeep in mind that there is more than one way to get to the correct answer. We have shown you a few different methods to add, subtract and multiply, but there are many other methods.

Try these or other methods to see if you like them. Perhaps you can invent your own.

Arithmetic
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