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Your post # 691 is correct. Good. Well done. I will give you a chance to read the next post.
Sorry about that my computer crashed so it then wasted several minutes rebooting.
I think we had better discuss multiplication of fractions. This is relevant to percentages to a certain extent.
Right let us take an example:
The answer is to multiply top and bottom numbers together....
So the numerators (top) are 2 x 1 = 2
The denominators (bottom) are 3 x 2 = 6
So the result is:
This simplifies to:
20 % can be thought of as the same as the following fraction:
Try cancelling or simplifying this fraction as far as you can go. What do you get ?
Okay the answer is that 20 should be divided by 5. The answer is four.
That is to say:
Any number divided by 1 is itself.
Therefore:
What whole number is the fraction ....
equal to.
Have you been taught about multiplying fractions ?
Okay here are a few notes on that:
one fifth of 20 is:
I will have to try to get better at using Latex. I am struggling with using it to write fractions.
Right now: Here is another question ..... What is one fifth of 20 ?
So what is 0.2 x 20 ?
What is 20 % of 20 ?
When I look at the number 0.2 I would automatically know that it is one fifth, but that is not necessarily obvious.
You can re-write 0.2 as a fraction by the fact that it is the same as 2 tenths.
So using some Latex:
Right here is a related question to test you on multiplying by a decimal:
What is 20 x 0.2 ?
Right. OK. Now I will give you a worked example for that. Some people reading this would know at once the answer, but
I will explain how I would think about this question (in a way that works when the numbers are not quite so nice).
The percentage 10 % can be thought of as being like the decimal 0.1
If you say "calculate 10 percent of" something then you mean calculate 0.1 times something.
In other words we are trying to work out 50 x 0.1 and then adding that to 50.
So I happen to know that 50 x 0.1 = 5
So that means that 10% of 50 is in fact 5
Then when you add that on to the number 50 you get 55
So in answer to my original question the answer is 55.
Now are you happy with the concept of multiplying by a decimal like 0.1 ?
Can you see that if you multiply by 0.1 you are dividing the number by 10 ?
EDIT:
Right OK. Percentages.
Now, if I have a number like say 50 and you had to add 10% would you know how to do that ?
(I am trying to get an idea of how much you know already)
Right now according to what I have read on something you wrote to me about earlier your next topic
is "Factors and Multiples". Is that the one that you consider to be next. Or is there something else ?
Yes well done. Now what topic do you want to do ?
Multiplication ? Division ? Or the next topic ? (If so which one ?)
The " 1 6 1 " bit is now correct. Well done.
Now because the answer depends upon this bit being correct you should really redo the addition.
In other words what effect does this have on the final answer ?
Hi steveb mandy here i have done the sums you left me ok?
2 3
2 7
_____
1 5 1
4 6 0
_____
6 1 1
_____That one is wrong, but it is not too far out. You have I think made a minor error with either
the carry of 3 x 7 = 21 and carried a "1" instead of "2". Or maybe you accidentally put in
7 x 2 as 13 rather than 14. The number at the top in the middle bit you have put as " 1 5 1 ".
What did you carry at each stage in this bit ? Do you want to try that bit of it again ?3 6
3 4
______
1 4 4
1 0 8 0
______
1 2 2 4
______Very good. That is correct.
1 6 7
2 5 4
______
6 6 8
8 3 5 0
3 3 4 0 0
_________
4 2 4 1 8
________Very good again, although you have written them a bit out of alignment on the screen you
have got all of the middle bits correct and added them correctly.So you may wish to just look at the first one and see the mistake you made in the first middle number.
Actually just to correct that last bit I am early. So ready when you are.
Okay. I have made a few notes on some multiplication for you to try they are:
683 x 6 ?
781 x 3 ?
687 x 7 ?
See you at 7pm, I might be a little late for that but not by much. Bye
Right. I kinow what you mean by that and you may well have put the right number at the top, but
it is a good idea to try to avoid putting something like " 9 x 9 = 1 " because although it is indeed 1
that we are trying to get here strictly speaking 9 x 9 is 81.
You can probably see that the answer at the top becomes: 0 8 3 1 so the answer is 831.
Shall we try a multiplication for a change how about 683 x 6 ?
First of all how should we lay out this multiplication ?
Yes 3 x 9 = 27.
So the "3" bit of that goes at the top (so that becomes 083 .... ).
Now the subtraction 27 - 27 = 0
So all we have now is 9 which is dropped down with an arrow.
Now we need a multiple of 9 which equals 9. Any comment ?
Right how about we just finish off that division.
The situation was that we have 27 left and we need a multiple of 9 for that.
What number do you think we should choose ?
Sorry about that. Sometimes I am writing my next post and during that time you are doing yours.
When I post mine I see yours after I have submitted mine. Then I see that my post no longer makes sense.
But yes your answer in #643 was correct it is 42. This is one that you are going to have to focus on a bit more.
No. 6 x 7 = 42.
I have thought of an idea. You could take a note of any times table that you cannot do
correctly and focus your attention on those ones perhaps.
0 8
---------------
9 | 7 4 7 9
0
---
74
72
---
2 7 any ideas for the next step here? I have seen that number before somewhere (????)
6 x 7 is not 35.
All of the rest of those tables were correct though. Well done. So do you want to try again with 6 x 7 ?