Friendly Tens
What friendly ten is close to 38?
Answer: 40
38 + 22 → What friendly pair makes it easier?
Answer: 40 + 20 = 60
Explain how you know 38 + 22 can become 40 + 20
Because 38 is close to 40, we can take 2 away from 22 and add it to 38.
That makes 40 + 20, which is easier to add in our heads.
What are addends?
Addends are the numbers we add together to find a total or sum.
Which number is closest to 50: 49 or 46?
Answer: 49
46 + 39 → How can we change it?
Answer: 45 + 40 = 85
Why do we look for friendly tens?
Because numbers that end in zero are easier to add!
What does compensation mean?
Compensation means changing one number to make an easier number to add, and then adjusting the other number so the total stays the same.
What number should we add to 27 to make it a friendly ten?
Answer: 3
27 + 48 → How can we make it friendly?
Answer: 30 + 45 = 75
What happens if we move too much from one number?
If we move too much, the math doesn’t balance — the total changes
In the number 38 what number is in the tens place?
the 3 is in the tens place.
True or False: 59 is already a friendly ten.
Answer: False
Explain how compensation keeps the total the same
Compensation keeps the total the same because when we take a small number away from one addend, we give that same amount to the other addend — so the total doesn’t change.
How does the compensation strategy help you add in your head?
It helps me add faster because I can make easy tens.
In tyhe number 43, what number is in the ones place?
The number 3