1. Multiple ways to add and subtract I am learning to use multiplication and division to solve addition and subtraction problems.

2. Below is an array. You can see it has 4 rows and 6 faces in each row. We can refer to this as 4 X 6 = 24 Here is an array showing 2 X 6 = 12 Let’s add the two arrays together. 4 X 6 = 24 plus 2 X 6 = 12. 24 + 12 = 36 Watch what happens when we combine the two arrays. Now we have 6 X 6 = 36 Let’s look a little more closely. (4 X 6) + (2 X 6) = 6 x 6 We can combine the 4 and the 2 together because they both have the common multiple of 6.

3. Now let’s use this strategy for an actual question. Craig has 28 marbles, Sarah has 9 marbles and Joe has 45 marbles. How many marbles do they have in total? 27 + 9 + 45 = ?Step 1: Think of a number which is a factor of all these numbers. 9 (3 X 9) + (1 X 9) + (5 X 9) Step 2: We can combine these to make the question below. 9 X 9 = 81

4. We can also use this strategy for subtraction. Alicia has read 56 books this year. 24 of these were fiction books. How many of these were not fiction. 56 – 24 = ? Step 1: Think of a number which is a factor of both 56 and 24. Step 2: (7 groups of 8) – (3 groups of 8) = (4 groups of 8) 8 (7 X 8) - (3 X 8) = ? 4 X 8 = 32

5. Now try these questions on your own. Remember to first find a common factor. Need some more practise? Try Pg68 of Teacher Tools Addition and Subtraction Book Numeracy resourcesNumeracy resources 1) 66 + 42 + 12 = ? 2) 25 + 35 + 50 = ? 3) 16 + 28 + 12 = ? 4) 81 - 63 = ? (11 X 6) + (7 X 6) + (2 X 6) = 20 X 6 (5 X 5) + (7 X 5) + (10 X 5) = 22 X 5 (4 X 4) + (7 X 4) + (3 X 4) = 14 X 4 (9 X 9) - (7 X 9) = 2 X 9 120 110 56 18