Key Concepts
- Add numbers using place value.
- Use properties of operation to find the sum.
- Solve few model questions related to addition by using place
Place Value Blocks
Question 1:
Represent the number 58 using place value blocks.
Answer:
58 is written as 5 tens and 8 ones.
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Question 2:
Elena picked 38 flowers from the garden. Mary picked 25 flowers from the same garden. How many flowers did they pick in all? Use place-value blocks to find the sum.
Answer:
Flowers picked by Elena = 38
Flowers picked by Mary = 25
Total flowers picked by Elena and Mary is the sum of 38 and 25.
Let’s use place-value blocks to find the sum of 38 and 25.
38 is written as 3 tens and 8 ones.
25 is written as 2 tens and 5 ones.
The sum of 38 and 25 = 38 + 25
Join the tens and ones of 38 and 25
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Regrouping 13 ones as 1 ten & 3 ones
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38 + 25 = 63
So, the total number of flowers picked by Elena and Mary is 63.
Representation of 2-digit numbers using place value blocks (dots and lines)
Place Value Block
We can represent the addend using quick drawing as lines and dots.
Representation of a single dot as 1 one.
Representation of single line as 1 ten.
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Remember:
10 ones combine to make 1 ten.
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Example 1:
Represent the number 48 using the place value block.
Answer:
48 is written as 4 tens and 8 ones.

Example 2:
Represent the number 72 using the place value block.
Answer:
72 is written as 7 tens and 2 ones.
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Sum of the 2-digit numbers using the place value blocks (dots and lines)
Example 1:
Find the sum of 34 and 55.
Solution:
One way:
34 is written as 3 tens and 4 ones.
55 is written as 5 ones and 5 tens.
The sum of 34 and 55 is given as below:
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34 + 55 = 89
So, the sum of 34 and 55 is 89.
Another way:
To find the sum of 34 and 55.
34 is written as 3 tens 4 ones.
55 is written as 5 tens 5 ones.
The sum of 34 and 55 is:
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8 tens and 9 ones is 89.
So, the sum of 34 and 55 is 89.
Example 2:
Find the sum of 43 and 19.
Solution:
One way:
Use quick drawing for addends.
And then join tens and ones.
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Regroup 12 ones as 1 ten & 2 ones.
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Another way:
To find the sum of 43 and 19.
43 is written as 4 tens 3 ones.
19 is written as 1 ten 9 ones.
The sum of 43 and 19 is:
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12 ones is 1 ten 2 ones
5 tens 1 ten 2 ones
50 + 10 + 2 = 62
So, the sum of 43 and 19 is 62.
Model question related to the sum of 2-digit numbers using place value block (dots and lines)
Example:
Kim counts 45 buttons. Then he counts 27 more buttons. How many buttons does Kim count in all?
Answer:
Number of buttons Kim counted in the first = 45
The number of buttons Kim counted the next time = 27
Total number of buttons Kim counted in all = Sum of 45 and 27
One way:
Let’s find the sum of 45 and 27 by drawing blocks for addends.
And then join tens and ones.
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Regroup 12 ones as 1 ten and 2 ones.
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45 + 27 = 72
So, Kim counted 72 buttons in all.
Another way:
To find the sum of 45 and 27.
45 is written as 4 tens 5 ones.
27 is written as 2 ten 7 ones.
The sum of 45 and 27 is:
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12 ones is 1 ten 2 ones
6 tens 1 ten 2 ones
60 + 10 + 2 = 72
So, Kim counted 72 buttons in all.
Activity
Circle all the number pair in the box that match that sum.
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Exercise
Question 1:
Find the sum of 27 and 43. Draw place-value blocks to explain your work.
Question 2:
Find the sum of 52 and 39. Draw place-value blocks to explain your work.
Question 3:
In a class there are 30 desks and 46 chairs. How many desks and chairs are there in total?
Question 4:
Sasha plants 24 trees. Monica plants 38 trees. How many trees do they plant in all?
Concept Map
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What we have learned
- Add numbers using place value blocks.
- Add numbers using properties of operation.
- Solve model question using place value blocks.
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