Welcome to Week 4 of Virtual Guru Math Suhruth Vuppala Let’s Review What We Learned Last Time What is the area of something? ● The area of a shape is how much space the shape takes up What is the perimeter of something? ● The perimeter of a shape is the length of the whole outside line or border of the shape ● The perimeter can usually be found by adding up all the side lengths of a shape How do you find the area of a square ● To find the area of the square you take one of the side lengths and multiply it by itself ● Let’s take the example of the square from two slides before. It has a side length of 5 centimeters, so you do 5x5 and you get the area ● What is the area of the square? How do you find the area of a rectangle? ● To find the area of a rectangle, you take the length of the top/bottom segments and multiply it by the length of the left/right segments ● Let’s use the example below. It has a right side length of 3 centimeters and a bottom side length of 8 centimeters. That means the area is 3x8 centimeters ● What is the area? How do you find the perimeter of a square? ● To find the perimeter of a square, you have to take one of the side lengths and multiply it by 4 ● Let’s again use the example from two slides before. It has a side length of 5 centimeters, so 5x4 is the perimeter of the square ● What is the perimeter? How do you find the perimeter of a rectangle? ● The perimeter of a rectangle can be found by doing 2 times the sum of the left/right and top/bottom ● In the example below, the right side length is 3 centimeters and the bottom side length is 8 centimeters. So the perimeter of the rectangle is 2(3+8) ● What is the perimeter? Review Questions 1. How do you find the area of a square? 2. How do you find the perimeter of a square? 3. How do you find the area of a rectangle? 4. How do you find the perimeter of a rectangle? 5. How do you find the area of a triangle? Let’s go over the Homework What does it mean for something to be ‘divisible’? ● A number is divisible by another number only if it can be divided and there is nothing left over. ● For example: 6 ÷ 3 = 2, therefore 6 is ‘divisible’ by 3 ● Here’s another one: 8 ÷ 4 = 2, therefore 8 is ‘divisible’ by 4 ● Is 9 divisible by 2? What are the divisibility rules? ● The divisibility rules are a set of rules we can use to help us decide whether a number is ‘divisible’ by another number. ● We will learn the divisibility rules for whether a number is divisible by the numbers 1, 2, 3, 4, 5, 6, 9, and 10. ● By learning these rules, it’ll make division easier for us. ● Later on, we will learn something called ‘factoring,’ and these rules will help us out with that. What is the divisibility rule for 1? ● The divisibility rule for 1 is that all numbers are divisible by 1. ● For Example 1,2,3,4,5 and so on are divisible by 1 because anything divided by 1 is itself ● Is 11 divisible by 1? ● Is 3,759 divisible by 1? ● Is 9,000,000 divisible by 1? What is the divisibility rule for 2? ● A number is divisible by 2 if it is even. ○ Take a look at the last digit of the number (the number in the ones place) ○ Is it an even number? ○ Remember: 0, 2, 4, 6, and 8 are even number ○ If the last digit is an even number, then you can say that the number is ‘divisible’ by 2! ● Here’s an example: ○ Let’s take a look at the number 46. ○ The number which is in the ones place (which is 6) is an even number ○ Therefore, the entire number 46 is divisible by 2. It can be divided by 2 and have nothing left over. ● Is the number 328 divisible by 2? What is the divisibility rule for 3? ● A number is divisible by 3 if the sum of the digits is a multiple of 3. ● For example, let’s look at the number 81 ○ Now let’s add the digits which make up the number 81 (8 and 1) ○ 8 + 1 = 9 ○ Can 9 be divided by 3? Yes, it can ○ Therefore we can say that 81 is divisible by 3. ● Here’s an example of a number which is NOT divisible by 3. ○ 22 is not divisible by 3 because 2+2 is 4 and 4 divided by 3 has 1 left ● Is 33 divisible by 3? What is the divisibility rule for 4? ● A number is divisible by 4 if the last two digits of the number (the number in the tens and ones place) are divisible by 4 ● For example: ○ 512 is divisible by 4 because the last two digits of 512 make up the number 12 and 12 is divisible by 4 because when you divide it by 4 you have 3 exactly with nothing left. ● Here’s an example of where a number is not divisible by 4 ○ 111 is not divisible by 4 because the last 2 digits are 11 and 11 is not divisible by 4 because when you divide it by 4, you will have 3 leftover. ● Is 316 divisible by 4? What is the divisibility rule for 5? ● A number is divisible by 5 if the last digit ( the number in the ones place) is either 5 or 0. ● For Example: ○ 100 is divisible by 5 because the last digit is 0 ● Here’s an example of a number not divisible by 5: ○ 101 is not divisible by 5 because the last digit is 1 and not 0 or 5 ● Is 415 divisible by 5? ● Is 918 divisible by 5? What is the divisibility rule for 10? ● A number is divisible by 10 only if the last digit is 0. ● For Example, 600 is divisible by 10 because its last digit is 0 ● 401 is not divisible by 10 because its last digit is 1 which is not 0 ● Is 1,000 divisible by 10? ● Is 1,385 divisible by 10? Jeopardy! https://jeopardylabs.com/play/divisibility-rules7 Homework ● Keep an eye out on your email and google classroom for the new homework of this week. ● If you have a gmail account which you would like to have added to the google classroom page, please let us know, and we will email you an invite or the class code. ● Thanks for coming! We hope to see y’all next week!.