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Are you ready? Here are the concepts we’re covering in math. Let’s see what you know! Mrs. Flynn’s Topic 3 Math Review Multiplying by Multiples of Ten 4 X 20 = ? Look for the basic fact to help you. 4 X 2 tens = 8 tens So… 4 X 20 = 80 Basic fact Basic fact Basic fact Practice Multiplying Tens 1. 3 X 2 tens = 6 tens (60) 2. 6 X 5 tens = 30 tens (300) 3. 8 X 6 tens = 48 tens (480) 4. 5. 6. 7. 7 7 6 4 X X X X 20 80 90 50 = = = = 140 560 540 200 Nicole builds 3 birdhouses in an hour & works 40 hours weekly. How many birdhouses does she make each week? 3 birdhouses X 40 hours = There are 20 chickens on John’s farm. Each lays 2 eggs each day. How many eggs can John collect each week? 2 eggs X 20 chickens X 7 days = Multiplying Using Patterns Look for the basic fact to help you. 3 X 3 hundreds = 9 hundreds So… Basic fact 3 X 300 = 900 Basic fact Basic fact Multiplication Patterns Use the same idea to help you multiply larger numbers. 6 X 4 = 24 6 X 40 = 240 6 X 400 = 2,400 6 X 4,000 = 24,000 Practice! Find each product. 1. 5 X 90 = 450 2. 70 X 700 = 49,000 3. 6 X 5,000 = 30,000 4. 600 X 70 = 42,000 5. 8,000 X 3 = 24,000 Estimate means… to find a number close to the exact number. Rounding to Estimate Products Cheyenne collects books. She has 8 boxes. Each box holds about 38 books. How many books does she have? (38 rounds to 40) Rounding to Estimate Products Christian collects books. He has 18 shelves. Each shelf holds about 115 books. About how many books does he have? (115 rounds to 100) (18 rounds to 20) Rounding to Estimate Products Corey collects football cards. He has 5 albums. Each album holds 45 cards. About how many football cards does Corey have? (45 rounds to 50) Now it’s your turn! 1. 2. 3. 4. 5. 6. 7. 567 X 5 674 X 22 7,881 X 6 3,580 X 3 6 X 251 4 X 3,679 72 X 1,814 600 X 5 = 3,000 700 X 20 = 14,000 8,000 X 6 = 48,000 4,000 X 3 = 12,000 6 X 300 = 1,800 4 X 4,000 = 16,000 70 X 2,000 = 140,000 Distributive Property with Arrays What is an array? An array is an arrangement of objects into rows and columns. 5 rows of 1 5 rows of 10 Practice! Draw arrays to help. 1. 73 X 7 70 X 7 = 490 3 X 7 = 21 490 + 21 = 511 2. 35 X 6 30 X 6 = 180 5 X 6 = 30 180 + 30 = 210 3. 59 X 4 50 X 4 = 200 9 X 4 = 36 200 + 36 = 236 4. 46 X 9 40 X 9 = 360 6 X 9 = 54 360 + 54 = 414 5. 26 X 3 20 X 3 = 60 6 X 3 = 18 60 + 18 = 78 Multiplication with Regrouping Step One: Multiply the ones & regroup. +3 Multiplication with Regrouping Step Two: Multiply the tens & add the extra tens. +3 Multiplication with Regrouping Try some with me! +2 +2= 23 Multiplication with Regrouping Try some with me! +1 +1= 36 Multiplication with Regrouping Try some with three digits! +1 +5 +5= +1= 17 49 Multiplication with Regrouping Try some with three digits! +1 +2 +2= +1= 18 25 Multiplication with Regrouping Try some multiplication with money! +3 +2 +2= +3= 37 10 Multiplication with Regrouping Try some multiplication with money! +3 +7 +7 +7= +7= +3= 79 39 11 What is the Associative Property? When the grouping of factors is changed, the product remains the same. What is the Commutative Property? When the order of factors is changed, the product remains the same. Multiplying 3 Factors The parentheses tell which factors to multiply first. I know you’re going to do this on a piece of paper, right? Multiplying 3 Factors The parentheses tell which factors to multiply first. And you can do this in your head, right? Multiplying 3 Factors The parentheses tell which factors to multiply first. It’s all switched up, but it’s the same idea… Multiplying 3 Factors If there are no parentheses, multiply the smaller numbers first. Okay. NO PROBLEMO, No parentheses? MAN! Pencil, paper, and practice! 1. 6 X 6 X 3 = 18 X 6 = 108 2. 3 X 9 X 1 = 3X9= 3. 8 X 5 X 6 = 30 X 8 = 240 27 4. 4 X 3 X 11 = 11 X 12 = 132 5. 7 X 0 X 21 = 0 X 21 = 0 Problem Solving Fun! To raise money for the food drive, Kaitlyn sold 5 boxes of cards. Connor sold 3 boxes of candy bars. If a box of cards costs $2.99 and a box of candy bars costs $5.25, how much did they earn? +4 +4 +1 2 Digit by 2 Digit Multiplication 36 X 23 Multiply the ones. 36 X 23 3 X 6 = 18 Regroup the ten. 3 X 3 = 9 and one more is 10. 1 36 X 23 108 36 X 23 108 1 Cross out the 1 after you use it. NOW THINK: “I am multiplying 36 X 20.” 36 X 23 108 st 1 THINK: “I am multiplying by tens so I need a zero.” 36 X 23 108 0 2 X 6 = 12 Put down the 2 and regroup the 1. 1 36 X 23 108 20 1 1 36 X 23 108 720 1 2X3=6 and 6+1=7 1 Cross out the number you regrouped after you add it. 1 36 X 23 108 720 Since multiplication is a form of addition, we need to group our answers together. Add the two partial products to get the final product. 8+0=8 0+2=2 1+7=8 36 X 23 108 + 720 828 Exponents The number that is repeatedly multiplied is called the ___________. The _________________ shows the number of times the base is used as a factor. The base is multiplied 3X Write in Exponential Notation 1. Four squared = 2. Two cubed = 3. 5 X 5 X 5 X 5 = 4. 4 X 4 X 4 X 4 X 4 = 5. 6 to the 5th power = Write in Standard Form 1. Four squared = = 4 x 4 = 16 2. Two cubed = = 8 3. 5 X 5 X 5 X 5 = = 625 4. 4 X 4 X 4 X 4 X 4 = = 1,024 5. 6 to the 3rd power = = 216