1. Mental Strategies

2. What are they?
These help with mental calculations using large numbers.

3. Addition
If you were asked to find the sum of 654 and 129, you could line them up and use a lot of pencil lead, or you could do it a lot quicker. There are may ways of doing this, but here are two of them: = = =783 Or = = =783

4. Multiplication
This is not really a mental strategy, but saves on calculations… I call it the stick method. Eg 426x43 Draw vertical sticks, a group of 4 then 2 then 6 Draw horizontal sticks on top of these, a group of 4 with a group od 3 under.

5. 426x43

6. 426x43
Now count the intersections

7. 426x43 16
Now count the intersections

8. 426x43 16
Now count the intersections 8

9. 426x43 12 16
Now count the intersections 8 6 24 18

10. 426x43
Now add on the indicated diagonals 16 12 8 6 24 18

11. 426x43
To get 16, 20, 30, 18 16 12 8 6 24 18

12. 426x43
Now add like this: 16 12 16 20 8 6 30 18 24 18

13. 426x43
Now add like this: 16 12 16 20 8 6 30 18
18318 24 18

14. 426x43=18318

15. There are many others…
This was just to make you aware that many, many methods are available to you to solve all problems in mathematics. Play around and see if you can come up with something that works for you…