# Written Calculation Methods for KS2

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Written Calculation Methods for KS2

Addition Begin to partition numbers to add. 45 + 23 = ?
= 60 (Partition the number and add the tens together first.) 5 + 3 = 8 (Add the units together.) = 68 (Add the total of the tens and the total of the units together.)

Use the expanded method to add a 3 digit and a 2 digit number.
100 188 Standard written method This method will then be used for adding larger numbers and decimals.

Subtraction Subtract a 2 digit number from a 2 digit number using partitioning. 47 – 24 = (Partition smaller number.) 47 – 20 = 27 (Subtract multiple of 10.) 27 – 4 = 23 (Subtract units from answer to previous number sentence.)

Subtract a 2 digit number from a 3 digit number with no exchange.
169 - 53 1 16

Subtract a 2 digit number from a 3 digit number with exchange.
Standard written method. 172 - 56 This column subtraction method will then be used for subtracting larger numbers and decimals ensuring that children sometimes estimate first.

How do I multiply a triple digit number by a double digit?
142 x 12 = ? 267 x 19 = ? 145 x 67 = ? 243 x 15 = ? I’m sure that you’ll agree that there are many methods that we can use. Which method do you feel most comfortable with? Try your method to solve one of the problems on this page. When you are finished, explain your method to your partner. 142 x 14 = ? 156 x 14 = ? 262 x 15 = ?

Here’s a new method for you to try!
My problem is: x 13 = ? Step one: Break the numbers up into their different parts by partitioning into hundreds, tens and units. 145 = 13 = Step two: Fill the numbers onto a grid like this. x 100 40 5 10 3

Begin to cross multiply each number filling the answer into the grid.
Step 3: Begin to cross multiply each number filling the answer into the grid. (This is just like filling in a multiplication square.) x 100 40 5 10 1000 400 50 3 300 120 15 Step 4: Add up each row of numbers and put your total at the side of the column. x 100 40 5 1450 1000 400 50 3 300 120 15 435

Step 5: Simply add the two numbers together to get your final answer. How easy is that? Challenge! Can you use this new method to solve the problem below? 134 x 15 = ? Therefore: 145 x 13 = 1885

Division To begin to use chunking to solve division number sentences.
18 ÷ 3 = 6 - 3 = 15 (3 x 1) - 3 = 12 (3 x 1) - 3 = 9 (3 x 1) - 3 = 6 (3 x 1) -3 = 3 (3 x 1) - 3 = 0 (3 x 1)

Use large chunk subtraction to solve division problems.
- 70 = 30 (7 x 10) - 28 = 2 (7 x 4) 518 ÷ 7 = 74 - 350 = 168 (7 x 50) = 28 (7 x 20) = (7 x 4) Sound knowledge of multiplication facts is needed and the use of a fact box as seen above will benefit some children. Children will again be encouraged to underline or circle their final answer. Fact Box 7 x 1 = 7 7 x 2 = 14 7 x 5 = 35 7 x 10 = 70 7 x 20 = 140 7 x 50 = 350 7 x 100 = 700

Any questions?