Lesson 20 in the "20 Free Maths Tutorials" series.

00:04 question 1
02:09 question 2
04:31 question 3
05:32 question 4
06:30 question 5
07:28 question 6
08:21 question 7
10:31 question 8
11:55 question 9
13:02 question 10
14:20 question 11
15:26 question 12
16:17 question 13
17:38 question 14
19:26 question 15
20:03 question 16

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TARGET AUDIENCE

The "20 Free Maths Tutorials" series is designed to work for various levels of ability. At the time of publication (in the early twenty-first century) it is roughly for someone aiming for a lowish to highish grade at GCSE in Britain (which is the exam taken when you are 16 years old).

There is a "20 Free Maths Tutorials" playlist on my YouTube channel which conveniently places all the videos in the correct viewing order.

My YouTube channel is...    / drduncanjames  

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MATHS CONTENT FOR OTHER LEVELS

I also have an "Improve Your Maths in 2 Hours" playlist which includes over 100 additional videos and a link to a free maths ebook (which is a PDF version of the manuscript of the paperback book) that complements the videos.

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OTHER EDUCATIONAL AND DOCUMENTARY VIDEOS ON MY YOUTUBE CHANNEL

My channel is home to other educational stuff... go and explore to find out more. I am constantly working on new content so it can be worth subscribing so as to be notified as I publish new things. On my channel (or in the pipeline) are videos about mathematics, nature, dance, history and languages.