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This content is taken from the National STEM Learning Centre's online course, Maths Subject Knowledge: Understanding Numbers. Join the course to learn more.
2.1

## National STEM Learning Centre

Skip to 0 minutes and 7 seconds PAULA KELLY: Welcome to week two of our online number course. In week one, we took a look at the brief history of numbers, exploring cuneiform, hieroglyphics, and Roman numerals. We explored place value and how that allows us to perform calculations and express very large and very small numbers. We also explored alternative number bases to the base 10 system we’re familiar with.

Skip to 0 minutes and 28 seconds MICHAEL ANDERSON: Remember that each week was a series of practise questions to help you consolidate what you’ve just learned. And just a quick reminder– check out the teacher resources from last week too.

Skip to 0 minutes and 38 seconds PAULA KELLY: This week, we’re going to have a closer look at times tables, explore factors of multiples and delve into the fascinating world of prime numbers. Let’s get started.

# Multiples, factors and primes

Welcome to week two.

Last week we looked at how number systems developed and saw that the number system we use today is a ‘place value’ system. In other words the value of a digit in a number depends upon its place within that number. The 8 in 28 represents eight units but the 8 in 184 represents eight tens i.e. eighty. We also saw that we can use any number base but generally, the number base we all use is base ten.

## Discussion

As a recap of where we’ve got to so far, here’s our starting question this week:

How would you explain to a student the importance of the zero in the number 108, but that the zero is not needed in the number 065 or the number 32.0?