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# Unit 3: Addition, subtraction, and estimation

1,600 possible mastery points

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## About this unit

The world of math is full of twists and turns but luckily, this unit on addition, subtraction, and estimation is here to help you navigate. Whether it's mastering the art of rounding or learning how to regroup, Khan Academy is your secret weapon for success.

### Learn

### Practice

- Round to nearest 10 or 100 on the number lineGet 5 of 7 questions to level up!
- Round to nearest 10 or 100Get 3 of 4 questions to level up!
- Round to nearest 10 or 100 challengeGet 3 of 4 questions to level up!

Level up on the above skills and collect up to 240 Mastery points

### Practice

- Estimate to add multi-digit whole numbersGet 3 of 4 questions to level up!

### Learn

### Practice

- Break apart 3-digit addition problemsGet 3 of 4 questions to level up!
- Add using groups of 10 and 100Get 3 of 4 questions to level up!
- Add on a number lineGet 3 of 4 questions to level up!
- Select strategies for adding within 1000Get 3 of 4 questions to level up!

Level up on the above skills and collect up to 480 Mastery points

### Practice

- Estimate to subtract multi-digit whole numbersGet 3 of 4 questions to level up!

### Learn

### Practice

- Break apart 3-digit subtraction problemsGet 3 of 4 questions to level up!
- Subtract on a number lineGet 3 of 4 questions to level up!
- Select strategies for subtracting within 1000Get 3 of 4 questions to level up!

### Learn

### Practice

- Subtract within 1000Get 3 of 4 questions to level up!

Level up on the above skills and collect up to 400 Mastery points

Level up on the above skills and collect up to 160 Mastery points

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Level up on all the skills in this unit and collect up to 1,600 Mastery points!