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How Do You Estimate the Square Root of a Non-Perfect Square?
What is the square root of 55?
Summary
- Square some whole numbers and see if we can find one that equals 55
- Since there isn't a whole number we can square to get 55, we need to estimate the answer
- To see how close our estimate was, we just need to square it and see if it's close to 55
- Since 56.25 is pretty close to 55, 7.5 is a good estimate for the square root of 55

Notes
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- Remember, to square a number is to multiply it by itself
- This is the same as taking a number to the second power
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- Perfect squares are the numbers you get when you square an integer
- So if you take the square root of a perfect square, you get a whole number
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- Since squaring is the opposite of square root, this means 5 is the square root of 25
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- Since squaring is the opposite of square root, this means 6 is the square root of 36
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- Since squaring is the opposite of square root, this means 7 is the square root of 49
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- Since squaring is the opposite of square root, this means 8 is the square root of 64
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- Since we have been trying all the whole numbers in order, this means there must not be a whole number we can square to get 55
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- When we squared 7, we got a number smaller than 55
- And when we squared 8, we got a number bigger than 64
- Since there are no whole numbers in between 7 and 8, there must not be a whole number we can square to get 55
- This means 55 is NOT a perfect square
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- The square root of 55 can't be a whole number
- But we know it's somewhere in between 7 and 8
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- Since 55 is in between 49 and 64, the numbers we got when we squared 7 and 8, the square root of 55 should be between 7 and 8
- 7.5 is right in between 7 and 8, so that's a good guess to start with
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- To see how close our estimate was, we just need to square it and see if it's close to 55
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