Reteach - Weebly

ReteachChapter 4Grade 5

NameDateLesson 1ReteachEstimate QuotientsTo estimate the quotient in a division problem, use rounding orcompatible numbers.RoundingCompatible NumbersEstimate 643 78.Estimate 322 53.Step 1Step 1Round the divisor to thenearest ten.What number is the divisor?Find compatible numbers for643 and 78. Compatiblenumbers are numbers that areeasy to divide mentally.643 78What is the divisor rounded tothe nearest ten?640 80Step 2Step 2What number is the dividend?Divide the compatible numbers.640 80 8So, 643 78 is about 8.What is the dividend rounded tothe nearest hundred?Step 3Divide the rounded numbers.300 50 6So, 322 53 is about 6.Estimate. Show your work.1. 512 522. 237 83 So, 512 52 is about .So, 237 83 is about.4. 807 933. 362 61 So, 362 61 is about30 . So, 807 93 is about.Grade 5 Chapter 4 Divide by a Two-Digit DivisorCopyright The McGraw-Hill Companies, Inc. Permission is granted to reproduce for classroom use.Round the dividend to thenearest hundred.640 and 80 arecompatible because64 8 8.

NameDateLesson 3ReteachDivide by a Two-Digit DivisorFind 592 30.Step 1Step 230 592Copyright The McGraw-Hill Companies, Inc. Permission is granted to reproduce for classroom use.Step 3130 592- 30 292You cannot divide 5 by 30.But you can divide 59 by 30.The first digit in the quotientwill be in the tens place.292 30 is about 10.Multiply 10 30 300.You cannot subtractbecause 300 292.1 30 59259 30 is less than 2. Write the1 above the tens digit of thedividend. Multiply: 1 30 30- 30 292Subtract 59 - 30 29.Compare the difference to thedivisor: 29 30Bring down the next digit of thedividend.Step 419 R2230 592- 30 292- 27022Try a lesser number in the divisor.Multiply 9 30 270.Subtract 292 - 270 22.Compare the difference to thedivisor: 22 30There are no more digits in thedividend, so write the remainder.Divide.R5 9 51. 23 -8 7 42. 38 --3. 23 554Grade 5 Chapter 4 Divide by a Two-Digit Divisor4. 58 92531

NameLesson 4DateReteachAdjust QuotientsSometimes when you estimate, a digit is placed in the quotient that istoo small or too large. In this case, you will need to adjust the quotient.Find 122 23.Step 1Estimate.Find compatible numbers for 122 and 23.122 23120 20 6So, 122 23 is about 6.Step 2Try the estimate.623 122-138Step 3Adjust.Try 5.5 23 122-1157So, 122 23 5 R7.Divide. Use another sheet of paper if necessary. Check each answer.1. 18 1083872. 43 5393. 98 2814. 42 5. 66 3876. 72 5597. 62 2388. 92 63232Grade 5 Chapter 4 Divide by a Two-Digit DivisorCopyright The McGraw-Hill Companies, Inc. Permission is granted to reproduce for classroom use.Because 138 122, the estimate 6 is too high.

NameDateLesson 5ReteachDivide Greater NumbersYou can use the standard algorithm or a calculator to dividegreater numbers.Find 12,420 365.Use compatible numbers to estimate.12,000 400 30So, 12,420 365 is about 30.Step 2 Divide the ones.Step 1 Place the first digit.Copyright The McGraw-Hill Companies, Inc. Permission is granted to reproduce for classroom use.3365 1 2,420- 1,0 951 471,242 365365 31,242 - 1,095147 36534 R10365 1 2,420- 1,0 951 4701,470 365-1 460365 4101,470 - 1,460 10Check for reasonableness. Because 34 R10 is close to the estimate,the answer is reasonable.Estimate. Then divide. Check for reasonableness.1. 62 18,9402. 59 10,8943. 28 18,906Estimate. Then divide using a calculator. If needed, round thequotient to the nearest whole number.4. 853 36,0045. 357 75,639Grade 5 Chapter 4 Divide by a Two-Digit Divisor6. 740 37,90733

NameLesson 6DateReteachProblem Solving: Solve a Simpler ProblemA rectangular backyard measures 50 feet by 60 feet and is covered withgrass. A rectangular pool that measures 30 feet by 20 feet is installed.How many square feet of grass will be left after the pool is built? Thearea of a rectangle can be found by multiplying base (length) by width.Step 1UnderstandBe sure you understand the problem.Read carefully.What do you know? The dimensions of the backyard are. The dimensions of the pool are.What do you need to find? You need to find how manyafter the pool is built.Make a plan.PlanThink of the problem in smallerparts to help solve it. It is easierto solve several simpler problems.Find the area of the backyard.60 ft50 ftPool20 ftFind the area of the pool.Then you can subtract to findthe area that will be left.3430 ftGrade 5 Chapter 4 Divide by a Two-Digit DivisorCopyright The McGraw-Hill Companies, Inc. Permission is granted to reproduce for classroom use.Step 2

NameLesson 6DateReteachProblem Solving: Solve a Simpler ProblemStep 3Carry out your plan.SolveFind the area of the backyard.A length width square feet(continued)Find the area of the pool.A length width square feetCopyright The McGraw-Hill Companies, Inc. Permission is granted to reproduce for classroom use.What must you do to find how many square feet of grass areleft after the pool is built? How many square feet of grass will be left?Step 4Is the solution reasonable?CheckReread the problem.Does your answer make sense?Solve. Use the solve a simpler problem strategy.1. A rectangular park is 80 meters by70 meters. A square piece of land nextto the park is purchased to enlarge thepark. The land is 30 meters on eachside. What will the total area of theenlarged park be?Grade 5 Chapter 4 Divide by a Two-Digit Divisor2. A rectangular rock garden is 18 feet by15 feet. Ms. Smithson wants to put arectangular pond that measures 6 feetby 4 feet in one corner of the garden.How many square feet of the rockgarden will not be covered by the pond?35

Sometimes when you estimate, a digit is placed in the quotient that is too small or too large. In this case, you will need to adjust the quotient. Find 122 23. Step 1 Estimate. Find compatible numbers for 122 and 23. 122 23 120 20 6 So, 122 23 is about 6. Step 2 Try the estimate. 6 23 122 -138 Because 138 122, the estimate 6 is .