Transcript Average ability

Average Ability
I am learning to use multiplication to add and subtract series of
whole numbers, fractions, and decimals.
0.7, 0.5
4, 17 etc.
1
2
2
3
Below is part of a hundreds board. Imagine putting counters on
pairs of numbers that add to 10.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
What did each pair add to?
11
How many pairs of counters did we use?
5
5 X 11 = 55
Add all the whole numbers together.
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 +10 = 55
Note how this is the same answer we got when we added up all the pairs.
Below is a list of numbers. Consider how they can be grouped
together to work out the total.
2, 4, 6, 8, 10, 12, 14, 16, 18, 20
How many groups are there? 5
What do the numbers in each pair add to? 22
What is 5 X 22 =? 110
So the sum of the numbers must be 110
Below is a list of numbers. Consider how they can be grouped
together to work out the total.
0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5
How many groups are there? 5
What do the numbers in each pair add to? 5.5
What are 5 groups of 5 and a
1
=?
2
So the sum of the numbers must be 27.5
Or 5 X 5.5 = ? 27.5
Below is a list of numbers. Consider how they can be grouped
together to work out the total.
1 , 2 , 1 , 1
1
3
3
3
,
2
2 ,
1 , 32
1
1
3 , 3
, 2 , 2 , 2
3
3
3
3
3
How many groups are there? 5 groups with 2 wholes left over.
What does each pair add to?
What are 5 groups of 4?
20
3 and 3 thirds (4 wholes)
Now add the 2 left over. 20 + 2 = 22
So the sum of the numbers must be 22
Now try these questions on your own. Add to following number sequences
together. Remember to look for a pattern.
Click again when you have
completed each question and
the answer will be displayed.
1) 1, 3, 5, 7, 9,11
2)
36
1 ,2 , 3 ,
3
1
2
1, 1 ,1 ,1
4 4 4
4
4
4
3) 0.3, 0.6, 0.9, 1.2, 1.5, 1.8, 2.1
7
8.4
Need some more practise? Try Pg67 of Teacher Tools Addition and
Subtraction Book Numeracy resources