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Hi Mallika,
I’m glad to see you are moving ahead with this topic.
In c you first find that a triple for angle CMB is 4,5,-
So you can get the required angle by doubling this and taking from the triple for 180 degrees.I hope this helps – let me know if it does not.
The problem in d is similar but you will need to introduce a value for the square’s side length, say 2.
Challenge Question 16
Squaring fractions
How can the general squaring method shown in Lesson 22 be applied to squaring fractions.
For example (3 5/6)^2 (that’s three and five sixths squared)?
Thanks for these excellent answers
Challenge Question 15
Two 3-figure numbers are multiplied to get a 6-figure number. But some of the digits get smudged, so we can only see:
321 x ??? = ???123
Can you find the missing digits?Hi Amara,
I’m not sure where you got the question from (if it’s from the free manual I think you may have copied it wrongly). Lesson 22 is about finding square roots of exact squares, so the method given will just give the first two figures of the answer, which for 5229 is 72.
49 is not the remainder until you have subtracted the duplex of 2 (the last figure of 72) from it. So 49-4=45: 45 is the remainder.
Hi Savita,
When you get 7 as the 2nd figure in the square root of 256 you can check if it is right, as we did in the video, by comparing the square of that 7 with the 16 at the end of 256.
Since 16 and 49 are not the same we can go back and, instead of saying 15/2 = 7 remainder 1, we can say 15/2 = 6 remainder 3.
Doing that you then see that you have 36 at the end of your 256 now and that is the same as 6 squared.
So the answer is 16. Writing 6 rem 3 instead of 7 rem 1 is something we will be using in lesson 25 next week, so you have anticipated that.
The full square root process comes up in lesson 29 where the above process is extended.
Sorry to hear about your situation Anupama. We are following it on the news.
I have sunbitted a ticket on your behalf.
Challenge Question 14
How can bar numbers be used to simplify division by 9 (lesson 18)?
For example, 3172 divided by 9.
Challenge Question 13
In Challenge Question 11 we looked at products like 47 x 67 (where the first figures add up to 10 and the last are the same), and the method was 4×6+7 / 7×7 = 3149.
How can this method be used to find 57 x 37?
[[perhaps this question should be barred]]
Hi Amara,
It happens to me as well. There are some technical problems so thank you for your patience. They will soon be resolved.
Challenge Question 12
A method was shown in Lesson 19 for converting temperatures from Fahrenheit to centigrade (subtract 32, add a tenth and halve), and, as mentioned in the lesson, this is approximate.
How can this be modified (by changing one word) so that the conversion is exact?
Challenge Question 11
Lesson 17 showed a neat way of finding products like 74 x 76 where the first figures are the same and the last figures add up to 10.
What about products like 47 x 67 where the last figures are the same and the first figures add up to 10?
(And how would you find 94 x 67, and 32 x 36 by this method?)
