To solve complex addition and subtraction problems using

To solve complex addition and subtraction problems using rounding to check my answer. Year 5 - Number (EXS) Lesson 3

LI: To solve complex addition and subtraction problems using rounding to check my answer. I can use my knowledge of rounding to make an estimate. I can use column method when adding or subtracting I can burrow/regroup when necessary to get my answer. Recap from the last lesson… Look at the skills and then quickly check your understanding. Previously, we looked how we could use rounding to estimate answers to addition and subtraction problems. Vocabulary Adding subtracting Altogether More than Left over How many more Column method Regrouping burrowing Estimating rounding Learning check: You do…. Let’s quickly recap the rules of using column method when adding and subtracting. . . 1. 2. 3. For column method, if you add two digits and the answer is more than 10, you must regroup by placing the ones of the number in the answer and carrying over the one. You cannot subtract a smaller digit from a larger digit. So for column method, if you come across this, you must burrow a “ten” from the next digit and add it to the smaller digit so that it can be larger. The digit you burrowed should then have one taken away from it. When estimating answers always round the numbers in the equation before solving it. Remember we estimate to make calculations easier. QUESTIONS: Estimate and solve: 1. 67321 + 10214 2. 39024 - 2941 = 3. 40233 - 12122 =

Answers QUESTIONS: Estimate and solve: 1. 67321 + 10214 = Estimate: 77000 Answer: 77535 2. 39024 - 2941 = Estimate: 36000 Answer: 36083 3. 40233 - 12122 = Estimate: 28000 Answer: 28111 Did you get these correct? If not, watch these videos from the last lesson of estimating adding and subtracting questions. If you feel confident, carry on with the slides.

LI: To solve complex addition and subtraction problems using rounding to check my answer. I can use my knowledge of rounding to make an estimate. I can use column method when adding or subtracting I can burrow/regroup when necessary to get my answer. Vocabulary Adding subtracting Altogether More than Left over How many more Column method Regrouping burrowing Estimating rounding Teacher Example… Fluency - estimating answers to addition and subtraction equations. Teacher example: Estimate and answer the following equation: 87231 - 28134 = Step 1: We are going to round both numbers in the equation to the nearest 1000 so that we can come up with an estimate: 87231 = 87000; 28134 = 28000 Step 2: We are now going to use our rounded values to find our estimate: 87000 - 28000 = 59000 Step 3: We are now going to use column method to find our actual answer to the equation: 87231 - 28134 = 59097 As you can see, we know our answer is correct because it is so close to our estimated answer. If you are struggling to round go back to one of the rounding lessons. If not, try some quick questions on the next slide.

LI: To solve complex addition and subtraction problems using rounding to check my answer. I can use my knowledge of rounding to make an estimate. I can use column method when adding or subtracting I can burrow/regroup when necessary to get my answer. Vocabulary Adding subtracting Altogether More than Left over How many more Column method Regrouping burrowing Estimating rounding Estimate the answer and then solve the following equations: 1. 2. 3. 4. 31892 + 29521 = 13911 - 10032 = 49222 + 50111 = 32910 - 29192 = Learning check: You do…. Answers: 1. Estimate: 62000 Answer: 61413 2. Estimate: 3000 Answer: 3879 3. Estimate: 99000 Answer: 99333 4. Estimate: 4000 Answer: 3718

LI: To solve complex addition and subtraction problems using rounding to check my answer. I can use my knowledge of rounding to make an estimate. I can use column method when adding or subtracting I can burrow/regroup when necessary to get my answer. Vocabulary Adding subtracting Altogether More than Left over How many more Column method Regrouping burrowing Estimating rounding Teacher Example… Application and reasoning questions. . . Application question: During a shopping trip, Alex buys the following items: Laptop (£ 1119), a phone (£ 855) and games console (£ 455). Before checking out, Alex uses her discount card which rounds her total to the lowest possible value. How much would Alex pay after using her discount card? Reasoning question: Sam thinks of two numbers that, when added together, would give an estimated answer of 50000, when rounded to the nearest 1000. He thinks the two numbers are 34945 and 14483. Are his numbers correct? Explain your answer. Watch the video to see how we can solve these problems.

LI: To solve complex addition and subtraction problems using rounding to check my answer. I can use my knowledge of rounding to make an estimate. I can use column method when adding or subtracting I can burrow/regroup when necessary to get my answer. Vocabulary Adding subtracting Altogether More than Left over How many more Column method Regrouping burrowing Estimating rounding Learning check: You do…. Q 1 At the end of the month Susan has to pay her bills. Her electricity bill is £ 892, her water bill is £ 1331 and council tax is £ 1899. Due to an error in the system, Susan is given a £ 943 discount off her total. Estimate how much Susan has to pay. Q 2 James thinks of two numbers that when rounded to the nearest 1000 it will give an estimated answer of 72000. His numbers are 65310 and 5921. Do you agree with his numbers? Explain your answer.

LI: To solve complex addition and subtraction problems using rounding to check my answer. I can use my knowledge of rounding to make an estimate. I can use column method when adding or subtracting I can burrow/regroup when necessary to get my answer. Vocabulary Adding subtracting Altogether More than Left over How many more Column method Regrouping burrowing Estimating rounding Learning check: Answers: Q 1 At the end of the month Susan has to pay her bills. Her electricity bill is £ 892, her water bill is £ 1331 and council tax is £ 1899. Due to an error in the system, Susan is given a £ 943 discount off her total. Estimate how much Susan has to pay. £ 900 + £ 1300 + £ 1900 - £ 900 = £ 3200 Q 2 James thinks of two numbers that when rounded to the nearest 1000 it will give an estimated answer of 72000. His numbers are 65310 and 5921. Do you agree with his numbers? Explain your answer. No. The value 65310 rounds to 65000 when rounded to the nearest 1000.

Well done! Now complete the worksheet below on the google doc. You can either write the answers on the google doc, or write it out on paper and send a picture of your work to your teacher. https: //docs. google. com/document/d/1 udi. SHuz. IHzv. Ul_q 5 b. ZFjhl. KE 2 o. KA 1 mlat. T-05 ae. Btr 8/edit Remember to log onto maths whizz as well this week!