I got a brand new dog,
I named him decompose,
He was really good at math
I suppose I suppose!

I took him straight to school,
To play a number game!
We watched him do his math,
We’d never be the same!

My teacher said to add,
To find sums in our head,
(in your head)
2 double-digit numbers,
She wrote them down in red!

37 plus 52
37 + 52
37 + 52
Add them in your head!

Decompose my doggie laughed,
He sniffed them with his nose,
He said don’t use your fingers,
Don’t add them with your toes,
When you’re adding up these numbers,
It’s best to decompose!

My teacher said, oh yeah,
Your dog is really bright,
My teacher said oh my, oh yeah,
He added them just right,
Decomposing works,
It really works so fine,
When you’re adding in your head,
You can use it every time!

Decompose every time
Decompose in your mind!

Now I’m breaking up my numbers,
I’ m finding tens and ones
It’s good for finding differences,
It’s great for finding sums!

Decomposition, my dog,
That was his name,
Adding tens and ones,
in his head, was his game!

I suppose I suppose,
I gotta’ decompose!

I took him straight to school,
To play a number game!
We watched him do his math,
We’d never be the same!

My teacher said to add,
To find sums in our head,
(in your head)
2 double-digit numbers,
She wrote them down in red!

37 plus 52
37 + 52
37 + 52
Add them in your head!

(wow that’s hard!)

Decomposition doggie laughed,
He sniffed them with his nose,
He said don’t use your fingers,
Don’t add them with your toes,
When you’re adding up these numbers,
It’s good to decompose!

Decompose
Decompose
Decompose
Decompose

He showed us how it worked,
It went a bit like this,
With this addition strategy,
We knew we’d never miss!

This is what you can do in your head to make adding easier

Decompose 37 into 30 (3 tens) and 7 ones
Decompose 52 into 50 (5 tens) and 2 ones

We add the 30 and 50 first to get 80 (adding tens is easy)
And then we add the 7 and 2 ones to get 9.
80 + 9 is 89

My teacher said, oh yeah,
Your dog is really bright,
My teacher said oh my oh yeah,
He added them just right,
Decomposing works,
It really works so fine,
When you’re adding in your head,
You can use it every time!

Decompose every time
Decompose in your mind!

Decomposition, my dog,
That was his name,
Adding tens and ones,
in his head, was his game!

My teacher said to add,
To find sums in our head,
(in your head)
2 double-digit numbers,
She wrote them down in red!

46 + 35
46 + 35
46 + 35
Add them in your head!

Now this is how my dog decompose added the numbers in his head.
First he decomposed 46 into its tens and ones to get 40 and 6

Then he decomposed 35 into tens and ones to get 30 and 5

Well he added the tens together- 40 and 30 is 70

Then he added the 6 and 5 ones and saw that he had 11 ones.

Well he might have seen that 70 + 11 is 81, but if he didn’t he could have decomposed again.

Start with the 70 + 11 and decompose the 11 into 1 ten and one 1.

then he could regroup that ten with the other tens to get 70 + 10 or 80

And he had his 1 left over, so he added that to 80 to give him 81.

That was fun!

Decomposition doggie laughed,
He sniffed them with his nose,
He said don’t use your fingers,
Don’t add them with your toes,
When you’re adding up these numbers,
It’s good to decompose!

Decompose
Decompose
Decompose
Decompose

He showed us how it worked,
It went a bit like this,
With this addition strategy,
we knew we’d never miss!

This is what you can do in your head to make adding easier

Decompose 46 into tens and ones to get 40 and 6 ones
Decompose 35 into 30 (3 tens) and 5 ones

We add the 40 and 30 first to get 70 (adding tens is easy)
And then we add the 6 and 5 ones to get 11.
Well that’s one more ten and one 1,

81

80 + 11 is 81

My teacher said, oh my oh yeah,
Your dog is really bright,
My teacher said oh yeah,
He adding them just right,
Decomposition works,
It really works so fine,
Decomposition works,
Use it every time!

My teacher said to add,
To find sums in our head,
(in your head)
2 double-digit numbers,
She wrote them down in red!

28 + 51
28 + 51
28 + 51

Add them in your head!

Now you try to add those in your head!

Wait 15 seconds

This is how I did it in my head

I combined the 20 and 50 to get 70
Then I added the 8 and 1 to get 9.
70 plus 9 is 7 9!

My teacher said to add,
To find sums in our head,
(in your head)
2 double-digit numbers,
She wrote them down in red!

29 + 36
29 + 36
29 + 36

Add them in your head!

Now you try to add those in your head!

Wait 15 seconds

This is how I did it in my head

I combined the 20 and 30 tens to get 50
Then I added the 9 and 6 ones to get 15.
50 + 15 = 65