Download math Club - Class 2 Discussion

Math Club – Grade 3
Class # 2 : 10/14/2014
GCF: Greatest Common Factor
It is the highest common FACTOR for 2 or more numbers
What is the GCF for 4 and 6?
What is the GCF for 6 and 12?
What is the GCF for 4 and 18?
What is the GCF for 12 and 18?
Practice 1: Greatest Common
Factor
Find GCF for the following:
a. GCF (6 and 9)
b. GCF (15 , 30)
c. GCF (10 ,11)
d. GCF (14 and 21)
e. GCF (16, 24)
Practice 2: Order of Operations
a. Evaluate: 12+ 5 x 3 – 10
b. Evaluate: 14 - 2 x 4 + 4 ÷ 2 – 4
c. Evaluate: 4 x (8 - 6) ÷ 2
d. Evaluate: (3+2) x (4 – 1) ÷ 5
e. Evaluate: 5 x 4 x 5 x 4 x 5 x 5 x 4
Practice Question 3
What number does N represent in equation
6 x 7 x 40 = 5 x 8 x N
Practice Question 4
Terry has 5 stickers in a row on a piece of
paper. The star is one to the left of the puppy.
The rainbow is to the right of the heart. The
puppy is three to the left of the kitten. Which
sticker is in the middle of the row?
Practice Question 5
Jorge is the first person standing in line. His
friend, Eli, is the 21st person on that same
line. How many people are standing between
them on line?
Practice Question 6
Grace chooses five different numbers from the
list 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. Two of those
numbers are 4 and 5, and they are the only
two numbers she picks that differ by 1. What
is the greatest possible sum of the five
numbers?
Practice Question 7
Find the value of
87 – 76 + 65 – 54 + 43 – 32 + 21 – 10
Practice Question 8
A 7 x 7 square is marked off into forty-nine 1 x 1
small squares. Each of the small squares along
the edges of the large square is painted blue.
How many small squares are painted blue?
Practice Question 9
The numbers 1, 2, 3, 4, 5 and 6 are placed in the
diagram, one in each circle. The sum of the
numbers along Side A is 13, along Side B is 13
and along Side C is 6. What number is in the
circle at the top of the diagram?
Side A
Side C
Side B
Practice Question 10
For a certain 3 digit number:
• the digits are in increasing order
• the difference of the greatest and least digits
is 7
• it is a multiple of 9 and greater than 200
Find the 3 digit number
APPENDIX
Factors
What are the factors of 4
1, 2, 4
What are the factors of 6
1, 2, 3, 6
What are the factors of 12
1, 2, 3, 4, 6, 12
What are the factors of 18
1, 2, 3, 6, 9, 18
Order of Operations
Observe the following priorities from left to right:
1. Do operations inside the brackets first, from left to right
2. Do Multiplication and Division next, from left to right
3. Do Addition and Subtraction , from left to right
Brackets  division & multiplication  addition & subtraction
Example
3 + 4 x 5 – 8 ÷ (9 – 7)
= 3+4x5–8 ÷ 2
= 3 + 20 – 4
=
19
Example: Order of Operations
Evaluate: 3 x 4 – 2 x 5 + 6 ÷ (2 + 1)
3 x 4 – 2 x 5 + 6 ÷ (2 + 1)  3 x 4 – 2 x 5 + 6 ÷ 3
3x4–2x5+6÷3 3x4–2x5+2
3 x 4 – 2 x 5 + 2  12 – 10 + 2
12 – 10 + 2  4
Tips and Tricks
Division by 2 If the last digit is divisible by 2, then the whole
number is divisible by 2
Division by 4 If the last two digits are divisible by 4, then the
whole number is divisible by 4
Division by 8 If the last three digits are divisible by 8, then the
whole number is divisible by 8
e.g.
536
Tips and Tricks
Division by 2
If the last digit of a number is ‘even’ number,
then the number is fully divisible by 2
Quiz: Which of the following is divisible by 2
456 or 442
321 or 442
Tips and Tricks
Division by 4
If the last 2 digit of a number are divisible by 4,
then the number is fully divisible by 4
Quiz: Which of the following is divisible by 4
456 or 442
336 or 444
Tips and Tricks
Division by 3
If the sum of digits of a number is divisible by 3,
then the number is divisible by 3
Quiz: Which of the following is divisible by 3
456 OR 334
Tips and Tricks
Division by 9
If the sum of digits of a number is divisible by 9,
then the number is divisible by 9
Quiz: Which of the following is divisible by 9
456 OR 334
Factors
What are the factors of 4
1, 2, 4
What are the factors of 6
1, 2, 3, 6
What are the factors of 12
1, 2, 3, 4, 6, 12
What are the factors of 18
1, 2, 3, 6, 9, 18
Order of Operations
Observe the following priorities from left to right:
1. Do operations inside the brackets first, from left to right
2. Do Multiplication and Division next, from left to right
3. Do Addition and Subtraction , from left to right
Brackets  division & multiplication  addition & subtraction
Example
3 + 4 x 5 – 8 ÷ (9 – 7)
= 3+4x5–8 ÷ 2
= 3 + 20 – 4
=
19
Example: Order of Operations
Evaluate: 3 x 4 – 2 x 5 + 6 ÷ (2 + 1)
3 x 4 – 2 x 5 + 6 ÷ (2 + 1)  3 x 4 – 2 x 5 + 6 ÷ 3
3x4–2x5+6÷3 3x4–2x5+2
3 x 4 – 2 x 5 + 2  12 – 10 + 2
12 – 10 + 2  4
Tips and Tricks
Division by 2 If the last digit is divisible by 2, then the whole
number is divisible by 2
Division by 4 If the last two digits are divisible by 4, then the
whole number is divisible by 4
Division by 8 If the last three digits are divisible by 8, then the
whole number is divisible by 8
e.g.
536
Tips and Tricks
Division by 2
If the last digit of a number is ‘even’ number,
then the number is fully divisible by 2
Quiz: Which of the following is divisible by 2
456 or 442
321 or 442
Tips and Tricks
Division by 4
If the last 2 digit of a number are divisible by 4,
then the number is fully divisible by 4
Quiz: Which of the following is divisible by 4
456 or 442
336 or 444
Tips and Tricks
Division by 3
If the sum of digits of a number is divisible by 3,
then the number is divisible by 3
Quiz: Which of the following is divisible by 3
456 OR 334
Tips and Tricks
Division by 9
If the sum of digits of a number is divisible by 9,
then the number is divisible by 9
Quiz: Which of the following is divisible by 9
456 OR 334
Factors
What are the factors of 4
1, 2, 4
What are the factors of 6
1, 2, 3, 6
What are the factors of 12
1, 2, 3, 4, 6, 12
What are the factors of 18
1, 2, 3, 6, 9, 18
Order of Operations
Observe the following priorities from left to right:
1. Do operations inside the brackets first, from left to right
2. Do Multiplication and Division next, from left to right
3. Do Addition and Subtraction , from left to right
Brackets  division & multiplication  addition & subtraction
Example
3 + 4 x 5 – 8 ÷ (9 – 7)
= 3+4x5–8 ÷ 2
= 3 + 20 – 4
=
19
Example: Order of Operations
Evaluate: 3 x 4 – 2 x 5 + 6 ÷ (2 + 1)
3 x 4 – 2 x 5 + 6 ÷ (2 + 1)  3 x 4 – 2 x 5 + 6 ÷ 3
3x4–2x5+6÷3 3x4–2x5+2
3 x 4 – 2 x 5 + 2  12 – 10 + 2
12 – 10 + 2  4
Tips and Tricks
Division by 2 If the last digit is divisible by 2, then the whole
number is divisible by 2
Division by 4 If the last two digits are divisible by 4, then the
whole number is divisible by 4
Division by 8 If the last three digits are divisible by 8, then the
whole number is divisible by 8
e.g.
536
Tips and Tricks
Division by 2
If the last digit of a number is ‘even’ number,
then the number is fully divisible by 2
Quiz: Which of the following is divisible by 2
456 or 442
321 or 442
Tips and Tricks
Division by 4
If the last 2 digit of a number are divisible by 4,
then the number is fully divisible by 4
Quiz: Which of the following is divisible by 4
456 or 442
336 or 444
Tips and Tricks
Division by 3
If the sum of digits of a number is divisible by 3,
then the number is divisible by 3
Quiz: Which of the following is divisible by 3
456 OR 334
Tips and Tricks
Division by 9
If the sum of digits of a number is divisible by 9,
then the number is divisible by 9
Quiz: Which of the following is divisible by 9
456 OR 334
Answers
Question #
Answer
1
(a) 3; (b) 15; (c) 1; (d) 7; (e) 8
2
(a) 17; (b) 4; (c) 4; (d) 3; (e) 40,000
3
N = 42
4
Heart
5
19
6
29
7
44
8
24
9
6
10
279