# Mathematics Then and Now - PowerPoint PPT Presentation

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Mathematics Then and Now. Most notable advancements in the early development of mathematics: Mayans Babylonians Egyptians Greeks Chinese. Ancient Math. Wrote on tablets Used two symbols for numbers Ones Tens Used a base 60 place system clocks (60 seconds, 60 minutes or

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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

### Ancient Math

Wrote on tablets

• Used two symbols for numbers

• Ones

• Tens

• Used a base 60 place system

• clocks (60 seconds, 60 minutes or

3600 seconds)

• circle (360°)

### Babylonians

Tablet with numbers

### Babylonians

1 set of 3600

52 sets of 60

30 sets of 1

1

52

30

• 1 ˟ 3600 = 3600

• 52 ˟ 60 = 3120

• 30 ˟ 1 = 30

• 6750

Try to write:

23

41

82

121

82 = 60 + 22

121 = 2 ˟ 60 + 1

### Play with Babylonian Numbers

Babylonian multiplication concentrated on perfect squares

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

2 22

### Babylonian Multiplication

Simple grouping system (hieroglyphics)

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 Mathematics

3000 + 200 + 40 + 4

= 3244

What are the following values?

52

21,238

### Egyptian Mathematics

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

### Egyptian Multiplication

Write down 1 and 50

150

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

2100

4200

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

8400

16800

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

### 18 x 50

900

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.

176

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

2152

4304

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

8608

161216

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

### 39 x 76

322432

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 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?

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

### Arithmetic

43

+ 25

+ 8

(60 + 8)

Partial Sums

Add the tens (40 + 20)

60

Add the ones (3 + 5)

68

268

Add the hundreds (200 + 400)

+ 483

+ 11

(600 + 140 + 11)

Partial Sums

600

140

Add the ones (8 + 3)

751

Lattice Sums

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 Change

124

Let’s look at some different methods to subtract numbers

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

### Subtraction

Counting Up-Hill

38 – 14 =

24

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

30

38

+8

+10

20

Record the numbers added at each interval:

(6+10+8=24)

+6

14

75

+ 61

75

– 38

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

Add 1 to the final result

136

+1

### Nines Complement

37

Let’s look at some different methods to multiply numbers

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

+

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 Product

Multiply 4 X 20 (ones by tens)

28

Multiply 7 X 4 (ones by ones)

1,728

Lattice Product

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 Tricks

We 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

6

20

6

We can multiply by four simply by doubling the value twice:

37 x 4

115 x 4

double

double

74

230

### Multiply by Four

double 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 Five

take 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 Eleven

Keep 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.