Helping your child with maths homework Back
The school has adopted four methods of carrying out mathematics calculations. These are taught from year 3 to year 6. Other methods may be taught at the end of year 6. If any of the methods are not clear feel free to talk to your child’s class teacher.
Multiplication
Children should learn, and be able to use by age 10, all the multiplication facts to 10x10.
16 x 5
Partition the 16 into 10 + 6, then set the calculation out as below
The steps in the calculation are as follows
10 x 5 =50
6 x 5 = 30
50 + 30 = 80 Hence 16 x 5 = 80
3 digit x 1 digit (HTU X U )
256 X 8 is approximately 260 x 10 = 2600
( The final calculation of 1600 + 400 + 48 can be done mentally or with appropriate jottings, or using the method children are using for addition. )
Subtraction
This method, also called complementary addition, builds on mental methods taught. It is based on finding the difference between 2 numbers by counting on from the smallest to the largest.
The two numbers being subtracted are positioned at each end of a number line. An addition to the smallest number is made to the nearest 10, this is noted on the line. Further additions are made, and noted, until the second of the two numbers being subtracted is reached. All the additions are then added mentally, giving the final answer.
56 – 27 (TU –TU)
+3 +10 +10 +6 = 29
-------------------------------------------
27 30 40 50 56
The size of jump may vary according to confidence. The next stage in the understanding of this calculation would be to make a more efficient jump of 20 from 30 to 50.
157 –78 (HTU – TU)
+2 +20 +57
78 80 100 157
Division
The aim is that children should know and use multiplication facts to 10x10, and know and use the corresponding division facts. The following method allows numbers to be divided even if all the division facts are not known.
The number being divided is positioned at the right end of a number line, 0 is placed at the other end. Jumps along the line are made in multiples of the divisor (the number being divided by), 7 in the example below. The number of jumps is totaled and recorded along with any remainder.
68 ÷ 7
7 7 7 7 7 7 7 7 7 [R5] "Nine sevens are sixty three remainder 5"
0 7 14 21 28 35 42 49 56 63 68
A more efficient method would be to use key facts as a starting point.
“I know that 5 x 7 = 35, so that will be my first jump”.
5 7 7 7 7 [R5]
x7 x1 x1 x1 x1
0 35 42 49 56 63 68
As confidence increases children may use other known tables facts to help them in their calculation.
I know 7 x 7 = 49 and I know 2 x 7 = 14
7 2 R5
x7 x7
----------------------------------------------------------------
0 49 63 68 68÷7 = 9 R 5
Addition
Children will be taught to mentally add number bonds for all numbers to 10, then 20. As they progress to adding two 2 digit numbers, they will be taught to partition the numbers, then add. Write the two numbers above each other, making sure units are above units and ‘tens’ are above ‘tens’. The calculations are listed below.
40 + 50 = 90
8 + 3 = 11
90 +11 = 101.
If this could not be attempted. Then 90 +10 = 100 then 0+1 =1, 100+1=101
48 + 53 = 101
48 + 53 --- 90 + 11 --- 101 |
Eventually children will be taught to add the least significant number first.