Mathematics Chapter 1: Addition & Subtraction with regrouping Grassy Lake Elementary School Third...
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Transcript of Mathematics Chapter 1: Addition & Subtraction with regrouping Grassy Lake Elementary School Third...
MathematicsChapter 1: Addition &
Subtraction with regroupingGrassy Lake Elementary School Third Grade
Created by: Mrs. Tamara Russell
Goals To identify and write related addition and subtraction
facts. To solve number sentences for missing addends. To add 2-digit numbers without regrouping. To subtract 2-digit numbers without regrouping. To use the problem solving skill choose the
operation.
Materials Scrap paper or white boards Pencils or expo markers Erasers or paper towels for the boards
Today’s Lesson By the end of today’s lesson, you will be able to add
and subtract two digit numbers using regrouping.
56+1571
62- 1547
151
Lesson Did you know that every
number has a home, just like you?
We call those numbers homes their place value.
In order to add or subtract two digit numbers we need to review place value!
Let’s go!
Let’s do some problems! You will need a white board, a marker and an eraser. Together we will do six problems – three addition
and three subtraction. When we are all done, we should know how to add
and subtract by regrouping! Let’s do it!
Two digit addition Always remember to line up
your numbers properly. Start at the right. (6 + 5) Put the sum of 6 + 5 in its
house. (11) Oops! Too many! Carry a number!
Now, add the numbers in the tens’ column. (5 + 1 + 1)
Put the sum of 5 + 1 + 1 in the tens’ column. (7)
56
+ 15
Tens Ones
17
1
Again? Always remember to line up
your numbers properly. Start at the right. (4 + 6) Put the sum of 4 + 6 in its
house. (10) Oops! Too many! Carry a number!
Now, add the numbers in the tens’ column. (2 + 3 + 1)
Put the sum of 2 + 3 + 1 in the tens’ column. (6)
64
+ 32
Tens Ones
06
1
Last time? Always remember to line up
your numbers properly. Start at the right. (2 + 9) Put the sum of 2 + 9 in its
house. (11) Oops! Too many! Carry a number!
Now, add the numbers in the tens’ column. (3 + 1 + 1)
Put the sum of 3 + 1 + 1 in the tens’ column. (5)
92
+ 13
Tens Ones
15
1
Let’s subtract! Always remember to line up
your numbers properly. Start at the right. (3 - 4) Oops!
You can’t subtract 4 from 3! Time to borrow!
Borrow ten from next door and make 13. And subtract a ten to make 6.
Now, subtract. (13 – 4) Put your answer in the ones place.
Last, subtract 6 – 3. Put your answer in the tens place!
43
- 37
Tens Ones
93
136
Again? Always remember to line up
your numbers properly. Start at the right. (2 - 4) Oops!
You can’t subtract 4 from 2! Time to borrow!
Borrow ten from next door and make 12. And subtract a ten to make 6.
Now, subtract. (12 – 4) Put your answer in the ones place.
Last, subtract 3 – 2. Put your answer in the tens place!
42
- 24
Tens Ones
81
123
Last time! Always remember to line up your
numbers properly. Start at the right. (5 - 9) Oops! You
can’t subtract 5 from 9! Time to borrow!
Borrow ten from next door and make 15. And subtract a ten to make 7.
Now, subtract. (15 – 9) Put your answer in the ones place.
Last, subtract 7 – 7. The answer is zero and does not change the amount in the number, so you don’t have to put it there!
95
- 78
Tens Ones
6
157
Independent work Complete these practice
problems on your white board. Raise your hand when you are done so that I can check your work!
You have ten minutes to work and then I’ll show you the answers.
2 4 6 4+ 1 6 - 5 8
2 3 7 8+ 4 8 - 5 9
4 0
1
7 1
1
6
5 14
1 9
6 18