Doubles and Halves
Lets learn all about it
Select a number from below and
double it
24
16
34
57
65
93
43
How did you get your answer ?
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.
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 300+40
• Double 300=600 Double 40=80 add them
together and you get 680 as your answer
to
Double HTU
260
Lets double the hundreds and then
double the tens and add them together.
• 200+200=400
• 60+60=120
• Added altogether 400+120=520
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.
THTU
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
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.
Work Begins here!