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### Course: Grade 8 math (FL B.E.S.T.)>Unit 2

Lesson 4: Approximating irrational numbers

# Comparing values with calculator

Let's use the technique of squaring to compare values. We first compare 22.9% to an arbitrary value, 0.3, and then square 0.3 to compare it to the square root of 0.45. This helps us understand which value is larger without needing a calculator.

## Want to join the conversation?

• How come when he squares the square root of 0.45 it remains 0.45?
• 0.45 squared is 0.2025, and the square root of 0.2025 is 0.45, so basically, a square root undoes a square, and vice versa. Here's another example of this: if we find the square root of the number 9, we get 3. 3 squared is 9, so we are back to the number 9.
Hope this helps :)
• Why did he round up to 30%, when 22.9% is closer to 20%?
• In most situations, it is better to round up. Say you needed 22.9% of a gallon of concrete to finish a sidewalk. It is hard to measure 22.9% of a gallon, but if you round down to 20% of a gallon, there would not be enough concrete to finish the sidewalk, so it would be better to round to 30% of a gallon so you would have enough concrete with some left over.
• Cant you just make .45 into a percentage which would be 45% and you automatically know that its greater than 22.9%?
• how is 22.9 less then 0.3? when you line up the decimals , wouldn't 0.3 be less then 22.9?
• It is 22.9%, so when you move the decimal two places, you get the equivalent of 0.229 which is less than 0.3.
• I'm using the on-screen calculator for first time, when I put in 8 then square root sign then = I get a pink bar across my answer window instead of an answer. What does this mean? How can I find the square root of 8 on this style of calculator?
• Hi! I know I'm super late, but maybe this will help someone else. Let's say you wanted to get the square root of 4. Here are the steps:
1. Click the square root symbol button
2. Click the button for number 4
3. Click the close parentheses button i.e. )
And whatever different number you have just follow these steps and replace the 4 with your different number.
• How did he get 0.3?
• since when did we put a percentage into a decimal
• right now lol