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Day 4: RoundingDescription: Rounding : Counting in units, tens, hundreds
Objective: The purpose of this module is to be very clear at what point when counting (in tens for example) do you change from being at 50 to being at 60
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Rounding just means that we are only counting certain things - In the following example we will be counting groups of tens of things.

For example. If I was driving my car and was asked how fast I was driving at some point, I might say I was going at 50 Km per hour or 60 km per hour. If I wanted to be very exact I might say 55km per hour or even 57 Km per hour.

I would not say that I was travelling at 57,126 metres and 17 cm per hour.

Firstly it would be ridiculous for me to suggest I could measure something that accurately, and secondly it's easier to give an approximation.

When measuring speed we usually give our answer to the nearest 10 km an hour.

This means that I'm only going to count my speed in 10s of Kilometeres per hour.

This means the only answers I can give are: 0Km/hr, 10Km/hr, 20Km/hr, 30Km/hr, 40Km/hr, 50Km/hr, 60Km/h... etc

In the picture belowI have highlighted my speed counting up to 57 Km/h

                                                                                                                       

 

            10             20 30 40 50 60?

In this second picture, I'm only counting in groups of ten.

The question is - Should I include the last group of ten?

The usual answer is - well, I was more than half way across that group so I will include it.

This is the usual way we round numbers.

In the above example, when counting in groups of 10 my speed of 57 Km/h was rounded to 60Km/hr.