18/1 Time to Learn ~ Odd and Even Numbers

18/1 Time to Learn!

Odd and Even Numbers

At the end of this lesson, I can:

• make a general statement about sums, differences and multiples of odd and even numbers

Do You Still Remember? ~ Even Numbers

• An even number is a number that can be divided into two equal groups.

• Even numbers end in 2, 4, 6, 8 and 0 regardless of how many digits they have

• A few examples of even numbers are:

  -22, -10, 0, 6, 18, 234.

• We know the number 5,917,624 is an even number because it ends in a 4!).

Do You Still Remember? ~ Odd Numbers

• An odd number is a number that cannot be divided into two equal groups.

• Odd numbers end in 1, 3, 5, 7, 9.

• A few examples of odd numbers are:

  -101, -17, 1, 9, 23, 985.

• Now, I need you to put a 4-digit number that is an odd number in the classroom. [Go back to 18/1 Time to Learn and type your answer in the comment box ;) ]

Properties of Odd and Even Numbers

Addition, Subtraction and Multiplication

Let's learn!

• The odd and even numbers have special properties regarding the algebraic operations (addition, subtraction and multiplication).

• We exclude division here because the division sometimes give you the result in fraction, while we are talking here about the special properties.

Addition ~ Two Even Numbers

• When we add two even numbers, the result is always an even number.

• For example,

  16 + 4 = 20

  256 + 4 = 300

• Note that 20 and 300 are both even numbers.

Addition ~ Two Odd Numbers

• When we add two odd numbers, the result is always an even number.

• For example,

  7 + 3 = 10

  13 + 77 = 90

• Note that 10 and 90 are both even numbers.

Addition ~ Odd and Even Numbers

• When we add an odd number to an even number (regardless of which number comes first), the result is always an odd number.

• For example,

  1 + 4 = 5

  8 + 21 = 29

• Note that 5 and 29 are both odd numbers.

Subtraction ~ Two Even Numbers

• When we subtract two even numbers, the result is always an even number.

• For example,

  28 - 10 = 18

  36 – 24 = 12

• Note that 18 and 12 are both even numbers.

Subtraction ~ Two Odd Numbers

• When we subtract two odd numbers, the result is always an even number.

• For example,

  9 - 5 = 4

  39 – 13 = 26

• Note that 4 and 26 are both even numbers.

Subtraction ~ Odd and Even Numbers

• When we subtract an odd number and an even number (regardless of which number comes first), the result is always an odd number.

• For example,

  10 - 5 = 5

  17 – 4 = 13

• Note that 5 and 13 are both odd numbers.

Multiplication ~ Two Even Numbers

• When we multiply two even numbers, the result is always an even number.

• For example,

  2 x 3 = 6

  4 x 10 = 40

• Note that 6 and 40 are both even numbers.

Multiplication ~ Two Odd Numbers

• When we multiply two odd numbers, the result is always an odd number.

• For example,

  5 x 9 = 45

  7 x 11 = 77

• Note that 45 and 77 are both odd numbers.

Multiplication ~ Odd and Even Number

• When we multiply an odd number to an even number (regardless of which number comes first), the result is always an even number.

• For example,

  3 x 8 = 24

  4 x 15 = 60

• Note that 24 and 60 are both even numbers.

Conclusion 1

Addition

General statements about sums:

• When you add two even numbers together, the result is always an even number.

• When you add two odd numbers together, the result is always an even number.

• When you add an odd number and an even number together, the result is always an odd number.

Conclusion 2

Subtraction

General statements about differences:

• When you subtract two even numbers together, the result is always an even number.

• When you subtract two odd numbers together, the result is always an even number.

• When you subtract an odd number and an even number together, the result is always an odd number.

Conclusion 3

Multiplication

General statements about multiples:

• When you multiply two even numbers together, the result is always an even number.

• When you multiply two odd numbers together, the result is always an odd number.

• When you multiply an odd number to an even number together, the result is always an even number.

Multiple Choice

What happens when an odd number is added to an even number?

• I get an odd number.

• I get an even number.

Open Ended

Give an example to show your answer in slide 22.

Multiple Choice

True or False?

Even + Even = Odd

• True

• False

Multiple Choice

True or False?

Even x Odd = Even

• True

• False

Multiple Choice

True or False?

Even - Even = Odd

• True

• False

We are done ;)

Let's proceed to doing the practices!