Everyday we play mental maths games. We are very good at adding on and taking away in our heads.
In P2 we use strategies like:
- counting on and back
- looking for the relationship between adding and taking away
- Re-ordering numbers to make the calculation easier e.g. 7+1 putting the bigger number first is the same as 1+7
- Understanding how important 10 is e.g. 17 is 10 more than 7, 14 is 10 more than 4.
In P3 we do all of those strategies and we are learning to use other strategies like:
- Rounding and adjusting. This strategy is useful when adding or subtracting numbers that are close to a multiple of 10 or 100: e.g. 27 + 9 is 27 + 10 + 1 (9 is rounded to 10 and then adjusted by subtracting 1)
- Partitioning. This strategy involves splitting a number into tens and units:
e.g. 46 + 23 =
46 + 20 = 66+3 = 69
- Using Inverse Operations. This strategy involves the relationship between addition and subtraction. e.g. 16 - 12 - 12 + ? =16