P3_Addition with regrouping in tens.pptx

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1. Review using column addition to add 2- and 3-digit numbers by regrouping tens Review of column addition and subtraction

2. How our teaching resources are designed for the classroom

3. I can use column addition to add numbers by regrouping tens.

4. regroup column addition

5. The process of unitising and exchanging between place values is known as regrouping . For example, 10 tens can be regrouped for one hundred; one hundred can be regrouped for 10 tens. Column addition is a way of adding numbers by writing a number below another.

6. Regrouping tens with 2- and 3-digit numbers Problems with regrouping in the tens Review using column addition to add 2- and 3-digit numbers by regrouping tens

7. In this lesson you will meet: Regrouping tens with 2- and 3-digit numbers Lucas Alex

8. Alex has been adding numbers using column addition. He is unsure about the sum of these two numbers. Regrouping tens with 2- and 3-digit numbers I’m a bit uncertain what to do here. The sum of the tens digits is greater than ten. If the sum of the tens digits is ten or greater, regrouping is needed. + 4 5 4 9 I know that 45 is close to 50 and 94 is close to 100 I know that 50 + 100 = 150 The answer is close to 150

9. Lucas uses Base 10 blocks to represent the problem. Regrouping tens with 2- and 3-digit numbers + I think I remember learning about regrouping in Year 3 If the sum of the tens digits is ten or greater, regrouping is needed. Let’s start by representing the problem. 45 + 94 = 139 I knew the answer was close to 150 There are more than 10 tens so I’ll regroup 10 tens as 1 hundred. 5 ones add 4 ones is equal to 9 ones. 4 tens add 9 tens is equal to 13 tens. The regrouped hundred is moved into the hundreds column .

10. Lucas uses column addition to find the sum of 45 and 94 Regrouping tens with 2- and 3-digit numbers + 4 5 4 9 45 + 94 = 139 Let’s calculate 45 + 94 5 ones add 4 ones is equal to 9 ones. 5 tens add 4 tens is equal to 13 tens. 9 3 How would you use regrouping with tens when you’re adding digits? 1 10 tens are regrouped as 1 hundred and written in the hundreds column .

11. Alex wants Lucas to show him column addition using different numbers. Regrouping tens with 2- and 3-digit numbers + 2 5 8 4 85 + 42 = 127 You’re right , Alex. Let me show you how to calculate 85 + 42 5 ones add 2 ones is equal to 7 ones. 8 tens add 4 tens is equal to 12 tens. 7 2 I think we need to regroup in the tens column in this calculation too. 1 10 tens are regrouped as 1 hundred and written in the hundreds column .

12. Use column addition to add 75 and 73 Regrouping tens with 2- and 3-digit numbers + 3 5 7 7 75 + 73 = 148 5 ones add 3 ones is equal to 8 ones. 7 tens add 7 tens is equal to 14 tens. 8 4 Start by adding the numbers with the smallest place value first. Write the addends with the same value digits in the same column . 1 10 tens are r egrouped into 1 hundred and written in the hundreds column .

13. Alex uses column addition to add two 3-digit numbers. Regrouping tens with 2- and 3-digit numbers 1 hundred add 2 hundreds add the regrouped hundred is equal to 4 hundreds. 172 + 294 = 466 6 6 7 2 2 4 + 1 9 4 1 2 ones add 4 ones is equal to 6 ones. 7 tens add 9 tens is equal to 16 tens. Start by adding the numbers with the smallest place value first. Try adding together 172 and 294 I’m going to add two 3-digit numbers where I have to regroup the tens. I’ll write the addends with the same value digits in the same column . 10 tens are regrouped as 1 hundred and written in the hundreds column .

14. Alex uses column addition to add a 2- and a 3-digit number. Regrouping tens with 2- and 3-digit numbers 4 hundreds add the regrouped hundred is equal to 5 hundreds. 451 + 57 = 508 8 5 1 7 + 4 5 5 1 1 one add 7 ones is equal to 8 ones. 5 tens add 5 tens is equal to 10 tens. Start by adding the numbers with the smallest place value first. Try adding together 451 and 57 I’ll write the addends with the same value digits in the same column . 10 tens are regrouped as 1 hundred and written in the hundreds column . 0 is written in the tens column .

15. Use column addition to add 254 and 160 Regrouping tens with 2- and 3-digit numbers 2 hundreds add 1 hundred add the regrouped hundred is equal to 4 hundreds. 254 + 160 = 414 1 4 5 4 1 + 2 6 4 1 4 ones add ones is equal to 4 ones. 5 tens add 6 tens is equal to 11 tens. 10 tens are regrouped into 1 hundred and moved into the hundreds column . Start by adding the numbers with the smallest place value first. Write the addends with the same value digits in the same column . The 1 in the tens column represents 1 ten and the 1 in the hundreds column represents 1 hundred.

16. Regrouping tens with 2- and 3-digit numbers 1) Calculate the sum of each pair of numbers. + 3 3 6 6 a) + 3 5 9 5 b) + 6 2 6 8 c)

17. 2 ) Calculate the sum of each pair of numbers. Regrouping tens with 2- and 3-digit numbers 1 3 + 6 7 4 1 a) b) c) 4 + 4 6 5 2 2 + 7 6 7 3 2 + 8 7 5 5 d) e) f) 2 3 + 9 2 3 5 3 7 + 2 8 3

18. Regrouping tens with 2- and 3-digit numbers 1) Here are the answers : + 3 3 6 6 a) + 3 5 9 5 b) + 6 2 6 8 c) 1 6 2 6 tens add 6 tens is equal to 12 tens. 10 tens are regrouped as 1 hundred. 1 1 8 4 1 1 8 4 1

19. 2) Here are the answers: Regrouping tens with 2- and 3-digit numbers 1 3 + 6 7 4 1 a) b) c) 4 + 4 6 5 2 2 + 7 6 7 3 1 7 3 3 1 9 3 1 7 3 6 6 tens add 4 tens is equal to 10 tens. The 10 tens are regrouped as 1 hundred and is written in the tens column .

20. 2) Here are the answers: Regrouping tens with 2- and 3-digit numbers 2 + 8 7 5 5 d) e) f) 2 3 + 9 2 3 5 3 7 + 2 8 3 1 7 5 6 1 6 1 8 1 7 7 8 tens add 2 tens is equal to 10 tens. The 10 tens are regrouped as 1 hundred and is written in the tens column .

21. Regrouping tens with 2- and 3-digit numbers Problems with regrouping in the tens Review using column addition to add 2- and 3-digit numbers by regrouping tens

22. Alex is trying to find the missing digit. Problems with regrouping in the tens There’s a missing tens digit. I need to work out what it is. 10 t ens have been regrouped into the hundreds column. The tens digits have a sum of 13 3 8 7 + 9 4 1 4 + 5 = 13 To find a missing part, subtract the other part from the whole. 13 − 4 = 9 The missing tens digit must be 9 1

23. Alex wants to find the missing digits in this column addition . Problems with regrouping in the tens There’s a missing tens digit and a missing hundreds digit. There’s a hundred regrouped into the hundreds column . The tens digits have a sum of 12 7 tens add tens is equal to 12 tens. To find a missing part, subtract the known part from the whole. 12 − 7 = 5 The missing tens digit must be 5 2 9 2 4 + 7 5 5 3 6 1 The hundreds digits have a sum of 6 + 3 + 1 = 6 I can subtract the known parts. 6 − 3 − 1 = 2

24. Find the missing digits. Problems with regrouping in the tens 6 6 2 3 + 8 8 3 4 7 1 Find the missing tens and hundreds digits. Don’t forget the hundred regrouped into the hundreds column . 8 tens add tens is equal to 16 tens . To find a missing part, subtract the known part from the whole. 16 − 8 = 8 The missing tens digit must be 8 The hundreds digits have a sum of 7 + 4 + 1 = 7 7 − 4 − 1 = 2 The missing hundreds digit must be 2

25. Alex and Lucas use digit cards to complete the column addition . Problems with regrouping in the tens We need to use two cards for the tens digits and a card for a hundreds digit. We can only use a card once in each solution. 1 ten add 2 tens is equal to 3 tens. 3 hundreds add 3 hundreds is equal to 6 hundreds. There are 3 tens in the sum. We could use the 1 and 2 cards as the tens digits. 3 7 3 2 + 2 1 5 3 6 8 9 6 7 4 5 2 3 1 There are 6 hundreds in the sum. We could use the 3 card as the missing hundreds digit. Is there a solution where we need to use regrouping ?

26. Alex and Lucas look for another solution. Problems with regrouping in the tens The tens digits of the addends could have a sum of 13 tens. 6 tens add 7 tens is equal to 13 tens. 10 tens are regrouped as 1 hundred and written in the hundreds column . 3 hundreds add 2 hundreds and the regrouped hundred is equal to 6 hundreds. 3 7 2 2 + 7 6 5 3 6 1 8 9 6 7 4 5 2 3 1 There are 6 hundreds in the sum. We could use 2 as the missing hundreds digit.

27. Find another solution that uses regrouping . Problems with regrouping in the tens Find a different solution to 365 + 272 = 637 9 tens add 4 tens is equal to 13 tens. 10 tens are regrouped as 1 hundred and written in the hundreds column . 3 hundreds add 2 hundreds and the regrouped hundred is equal to 6 hundreds. 3 7 2 2 + 4 9 5 3 6 1 8 9 6 7 4 5 2 3 1 There are 6 hundreds in the sum. You need to use 2 as the missing hundreds digit. Here is one possible answer.

28. 1) Find the missing numbers. Problems with regrouping in the tens 1 1 1 + 7 1 a) b) c) + 7 2 + 9 1 3 6 1 1 2 5 1 1

29. 2) Find the missing numbers. Problems with regrouping in the tens 7 5 2 1 + 8 4 5 1 a) b) c) 5 7 1 2 + 9 4 1 6 6 + 3 6 9 1

30. 3) Use digit cards to complete each column addition . O nly use a card once in each solution. How many different ways can you solve these? Can you use regrouping ? 4 5 4 2 + 2 1 3 8 8 9 6 7 4 5 2 3 1 a) 4 5 4 2 + 2 1 3 8 4 5 4 2 + 2 1 3 8 Problems with regrouping in the tens

31. 3) Use digit cards to complete each column addition . Only use a card once in each solution. How many different ways can you solve these? Can you use regrouping ? 2 9 + 2 1 7 8 9 6 7 4 5 2 3 1 b ) 2 9 + 2 1 7 2 9 + 2 1 7 Problems with regrouping in the tens

32. 1 1 1 + 4 7 1 a) b) c) 4 + 7 6 2 + 3 9 5 1 3 6 1 1 2 5 1 1 1 ) Here are the answers: 7 tens add 4 tens is equal to 11 tens. 10 tens are regrouped as 1 hundred and 1 is written in the tens column . Problems with regrouping in the tens

33. 7 5 2 1 + 9 8 4 2 5 1 a) b) c) 5 7 1 2 + 6 9 5 2 4 1 6 2 6 + 7 3 6 9 1 2) Here are the answers: 3 tens add 7 tens is equal to 10 tens. The 10 tens are regrouped as 1 hundred and is written in the tens column . Problems with regrouping in the tens

34. 3) Here are some possible answers: This solution doesn’t use regrouping. Both of these solutions use regrouping. 4 5 4 2 + 2 1 3 4 8 1 3 a) 4 5 4 2 + 2 1 3 3 8 9 5 4 5 4 2 + 2 1 3 3 8 8 6 1 1 Problems with regrouping in the tens

35. 3) Here are some possible answers: You have to use regrouping to get 2 tens in the sum. 2 9 5 7 + 2 1 2 1 7 9 3 b) 1 2 9 5 7 + 2 1 2 1 7 8 4 1 2 9 4 8 + 2 1 1 2 7 7 5 1 Problems with regrouping in the tens

36. When using column addition , start by adding the numbers with the smallest place value first. If the sum of the tens digits is ten or greater, regrouping is needed. Any complete hundreds are regrouped into the hundreds column. Review using column addition to add 2- and 3-digit numbers by regrouping tens