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Skill 8 of 13
In Progress

Decimals

You are maybe just below 2 metres tall. That is, 1 metre and some – but not 2. To be more precise you could choose to split 1 whole metre into for example 10 bits: ‘I am 1 whole metre and 8 of these bits tall’. Let’s write it short by using a point $.$ to separate the whole metres from the bits of metres:

$$1.8\,\mathrm m$$

These bits can also each be split into 10 even smaller bits so that you even more precisely can say ‘I am 1 whole metre and 8 of these bits and 4 of these bits’ bits tall’, written as:

$$1.84\,\mathrm m$$

  • So, your height consists of 1 whole metre and
  • 8 tenths of a metre1 as well as
  • 4 hundredths of a metre.2

Why do we split into exactly 10 bits? Why not 8 or 12? Because we have 10 numbers in our number system (0, 1, 2, 3, 4, 5, 6, 7, 8 and 9). We take maximum advantage of it.

If a small boy is not yet one full metre tall, then to keep the pattern we can simply write:

$$0.75\,\mathrm m$$

  • His height consists of 0 whole metres but
  • 7 tenths of a metre and
  • 5 hundredths of a metre.

We could continue like this if needed with ‘thousandths’, ‘tens of thousandths’ etc. Often people would call the numbers after the point decimals.[1] The number 7 is then the first decimal here and the number 5 the second decimal. And the point $.$ would be called the decimal point[2] or decimal separator.[3]


References:

  1. Decimal’ (encyclopedia), Wikipedia, 2019, www.wikipedia.org/wiki/Decimal (accessed May 2nd, 2019)
  2. Decimal point’ (encyclopedia/dictionary), Techopedia, www.techopedia.com/definition/18758/decimal-point (accessed May 2nd, 2019)
  3. Decimal and Thousands Separators’ (encyclopedia/dictionary), Oracle International Language Environments Guide, docs.oracle.com/cd/E19455-01/806-0169/overview-9/index.html (accessed May 2nd, 2019)