Lesson 1.1, Part 1
So what exactly are Digit Sums?
The Digit Sum of a number is the number you get when you add all the digits together, then add those digits together all the way until you have a single digit left between 1 and 9. You may be wondering about ’0′, it has some special properties which we will talk about in a future lesson. As you will come to see, there are patterns involving digit sums and shortcuts to make computing Digit Sums easier.
Why are they useful?
Digit Sums can find use in many things, a couple examples being: checking your answers, checking divisibility, and for dividing by nine.
How do you get them?
In order to get a Digit Sum all you have to do is add the digits. If the number you get is a single digit then your done, if not then you add them again until your left with a single digit. Take the number 26 for example; the Digit Sum would be 8 because 2 + 6 = 8.
Other Parts of Lesson 1.1
Part Two – Computing Digit Sums
Part Three – The Nine-Point Ciricle
Part Four – Casting Out the 9′s
[...] Part One I talked about what Digit Sums were, and why they are useful. Now I’ll show you some examples [...]
[...] Parts of Lesson 1.1: Part One – What are Digit Sums? Part Two – Computing Digit Sums Part Four – Casting Out the [...]
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