Tiêu đề Y2 Maths 2027b - 2024 Week 30 Notes.pdf ✅

Year 2 Maths – 2027b Term 4 Week 3 Notes Inverse means the opposite in effect, the reverse of something, in this case, an equation. Therefore, the inverse of Multiplying is Dividing, or the inverse of Division is Multiplication, because they are opposite in effect. When you multiply, what are you doing? You are finding the result for the total number of groups. When you divide, you are sharing the total number of things into equal groups. Multiplying can be "undone" by dividing. Let’s see how this works. Example: 5 × 9 = 45 can be reversed or undone by 45 ÷ 9 = 5 How do you use the same set of numbers to form a new equation? ____ ÷ ____ = _____ It works the other way around too, dividing can be undone by multiplying. Example: 10 ÷ 2 = 5 can be reversed by 5 × 2 = 10
Another example: If 27 apples are distributed into 3 baskets, each basket will get ___ apples: 27 ÷ 3 = _____ Let’s undo this by pouring all the apples out on the floor all over again using the multiplication sign: 9 apples came out from each of the 3 baskets 3 x ___ = 27 or ____ x 3 = 27 27 ÷ 3 = 9 Its inverse is: 3 x 9 = 27 or 9 x 3 = 27 7 baskets of 8 apples will give a total of ____ apples. 7 x 8 = _____ Let’s find the opposite effect by undoing the multiplication and use division to share the apples into equal groups of 7 A total of 56 to be distributed into 7 baskets: 56 ÷ 7 = _____ Or A total of 56 apples to be distributed into 8 baskets : 56 ÷ 8 = _____ Double check your answers to make sure that when we multiply, it gives a bigger result. When we divide, we’ll end up with a smaller number.
Try d. Find its opposite effect. Now try c: Now try a: The Inverse of Adding is Subtracting Adding moves us one way, subtracting moves us the opposite way. Example: 20 + 9 = 29 can be reversed by 29 − 9 = 20 (back to where we started) And the other way around: ____ - _____ = _____ Another example: 15 − 3 = 12 can be reversed by 12 + 3 = 15 (back to where we started)
Try d: Remember that we will get a bigger answer with addition Try e: Subtraction will involve a bigger number taking away a smaller number. Could you do it any other way with the same set of numbers? To measure something very long, we use Kilometre or km. Can you think of anything that we need to measure with km? • The distance from your house to the playground • The distance from your school to the nearest shopping centre etc. 1 How far is it from Bunbury to Tarton? _______km 2 From Tarton to Wandwich is ______ km