How do you calculate correctly with real world measurements

Based on the experience of the responder, to correctly calculate measurements in real-world. Firstly is to avoid errors as much as possible. Errors are what makes your measurement invalid and unreliable. There are two types of error which is called the systematic error and the random error. Each error has different sources. Words that were mentioned –invalid and unreliable are very important key aspects to determine that your measure is truly accurate and consistent. Some would recommend using the mean method, doing three trials in measuring and getting their mean, in response to this problem.
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Wednesday1.) < 2.) 1961015.)6.486.)68.761 can be rounded up to 69i can't truly see the rest and my next comment will be thursday