Doubles and Halves

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Doubles and Halves

• Lets learn all about it

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Select a number from below and double it
57
65
16
24
34
93
43
How did you get your answer ?
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This slide will show you multiples of 10 between
10 and 1000

• What will be in the units column when a number is
  a multiple of 10?
• Yes you are correct all multiples of 10 have a o
  in the units place.
• Examples are
• 90 130 220 340 520 630
• and on and on and on.
• The units column will have a zero.

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What is Double H T U
3 4 0

• How do you know the answer to this?
• First check to see is the number a multiple of
  10.
• To work it out you double the hundreds digit
  first, then double then tens digit and add them
  together.
• Lets partition the number 30040
• Double 300600 Double 4080 add them together
  and you get 680 as your answer to

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Double HTU 260

• Lets double the hundreds and then double the
  tens and add them together.
• 200200400
• 6060120
• Added altogether 400120520

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Lets half a number

• What is Half 1,420? Is this a multiple of 10?
• Lets apply the same method as before only in
  reverse.
• T H T U
• 1 4 2 0 Half the thousands 500
• Half the hundreds 200
• Half the tens 10
• Then add them altogether to get half 710
• The half of 1,420 is 710

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Lets get you to work !

• To double a number you must.
• Double the hundreds, the tens and then the units
  and add them all up.
• To half the number you must
• half all the hundreds, the tens and the units
  and add them up.
• Remember All multiples of 10 are easy! No need
  to worry about that units column.

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Work Begins here!