A new way of approaching maths

[Quickening]

Schools teach us to work out maths problems backwards with carrying crap. They teach us to solve problems right to left instead of left to right which is how we read.

Without pencil and paper, without calculation, within a few seconds of thinking, you can work forward instead of backwards.

672 + 127
six hundred seventy two plus one hundred twenty seven
seven hundred ...... seventy two plus twenty seven
seven hundred ninety ..... seven plus two
seven hundred ninety nine.
799

Another trick is you can work out what any two digit number times by 11 is immediately without pen paper/calculation/excessive thinking

36 x 11
3+6 = 9, pop that 9 in the middle of 36 and viola!
396

Try another;

99 x 11
9+9 = 18

Answer is NOT 9189..... but looks like this

1
989

Which is 1089 (after you add the 1 to the 9)


Whats 46 x 11? How about 23 x 11? 67 x 11 ?



















506, 253, 737!

Is this grabbing your attention yet? If it is... then I have the perfect PDF for you! (http://www.joyouslearning.info/lisa/Secrets%20of%20Mental%20Math.pdf) This is how we should have been taught - how to do it mentally without calculating crap.

[Quickening]

You can also do this with three digit numbers multiplied by 11

362 x 11

The answer still begins with a 3 and ends with a 2.
3+6 = 9 and 6 + 2 = 8
98 (and pop that in the middle for your answer)
3982

If it requires carrying its the same concept

476 x 11
4 + 7 = 11 and 7 + 6 = 13

11
4136

5236

[Syrenex Maer]

ok that just confused the hell out of me, but I was taught the other way, and I loved math so.....

Interesting concept I will look into it :)

[Ceres]

:imateapot

I find that confusing, but I have always had "isshews" with maths.
I like the montessori method of teaching maths actually.

[~*heket*~]

coming back to this!!!! cleaning before we go out for tea atm. Thanx Lisa, it looks fun!

[Quickening]

Its no more confusing than getting the answers for your 9 times table off your fingers. Anyone know that trick? Hold up both hands, 9 x 5 (put down your 5th finger - pinky finger of your left hand) count the number of fingers before the pinky (4) and then count the number of fingers after the pinky on the other hand (5) and you have your answer 45.

This is for 11 times table no matter how big the number gets
16 x 11 (add the digits of 16 which are 1 and 6 togehter and put the answer which is 7 in the middle of 16.) 176

12 x 11 = 1(1+2)2 = 132
25 x 11 = 2(2+5)5 = 275
42 x 11 = 4(4+2)2 = 462
352 x 11 = 3(3+5 and 5+2)2 = 3(6 and 7)2 = 3672

Why does the 9 times table work like that on your fingers? I don't know. Why does the 11x trick of adding together the digits of the number you are multipying by 11 with and putting it in the middle of said number work? I have NFI lol but every combination I have tried has given me the right answer when i've calculated it!

[Quickening]

Trick to square a two-digit number that ends in 5

1. The answer begins by multiplying the first digit by the next higher
digit.
2. The answer ends in 25.

Example - what is 25 x 25

So for step 1 of the trick: (2 is the first digit. the next higher digit after 2 is 3) so multiply that.... 2 x 3 = 6
For step 2 of the trick: (put 25 on the end of the number you get in step 1.) 625 is the answer.

Another example. What is 65 x 65? (next higher digit than 6 is 7) so;
6x7 = 42
Answer is 42 with 25 on the end ie 4225.

35 x 35 = (3x4) and add 25 on the end = 1225

95 x 95 = (9x10) and add 25 on the end = 9025

Testing a really big one.... what is the square of 535?
53 x 54 with 25 on end = 286225

Still works. I wonder how you can work out 53 x 54 in your head with tricks like the ones above. Had to use the calculator for that 53x54 problem. The pdf I linked to above shows you a whole bunch of tricks that you can use to work out math answers in your head with out pen/paper or calculator and without doing the problem "properly".

[~*heket*~]

These are great!!! I'll show Stylish if she every gets off the other computer ... and if I get off this one :lol

[Mama_Kaz]

Holy cow that confuzzled me a bit too but hey maths was never my strong suit :lol Perhaps if I sit down and do it like that with Jaz I might actually learn something I can retain :lol I will look into it more.

[Mama_Kaz]

Oh I also meant to ask Ceres - what is the Montessori method of learning maths?

[Ceres]

It involves wooden rods and golden beads :lol basically it's a physical representation of what the numbers "feel" like. So you have single beads, rows of 10, blocks of 100 etc. They can be used to teach multiplication and division to. I think for me I had trouble grasping the abstract concepts in maths, I struggled to remember what was 100 and what was 1000. This way you can actually feel the weight of 100 glass beads and relate it to the size and feel of a single bead, and so on.

[Mama_Kaz]

Yeah right...sounds interesting. Thanks for that :)