150 likes | 239 Views
Mental Strategies. What are they?. These help with mental calculations using large numbers. 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.
E N D
What are they? These help with mental calculations using large numbers.
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: 654+129=600+100+50+20+4+9=700+70+13=783 Or 654+129=653+130=683+100=783
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.
426x43 Now count the intersections
426x43 16 Now count the intersections
426x43 16 Now count the intersections 8
426x43 12 16 Now count the intersections 6 8 18 24
426x43 Now add on the indicated diagonals 16 12 8 6 24 18
426x43 To get 16, 20, 30, 18 16 12 8 6 24 18
426x43 Now add like this: 16 12 16 20 8 6 30 18 24 18
426x43 Now add like this: 16 12 16 20 8 6 30 18 18318 24 18
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…