Mental Addition-


Add these together in you head


a) =
b) =
c) =
d) =
e) =


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How to Add numbers together in your head

First you add the tens together and store your answer to one side in your head,.
  Add 38 and 67  
  So you start by looking at 
30 add 60 which is 90 and remember this part of the answer.  

  - Rules for Adding in your head- Always start with the largest value column you have ie- the tens column in a two digit number and the hundreds column in a three digit number.

You then add the units together 8 + 7 which is 15 and store this answer next to  your first part of the answer which was 90

 You then add the two answers you have in your head together starting with the larger number 90  which gives you 90 + 15 

So you add the two tens columns together first which is 90 + 10 = 100  and then you add the remaining units together     0 + 5 = 5  

So you are now left with 100 + 5 = 105                                              


Practice answering some more questions using your calculator.

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Lesson 4

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