There are ways to find approximate solutions by simplifying calculations. For example, it is not always necessary to give the exact number - you can give an approximate number by rounding up or down.

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Another way of rounding numbers is to count only the first few digits (maybe , or figures) that have a value attached to them. This method of rounding is called **significant figures** and itās often used with larger numbers, or very small numbers.

Rounding or to one decimal place seems sensible, as the rounded figures are roughly equal to the actual value.

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But what happens if you round a very small number to one decimal place?

( decimal place)

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This is not a useful answer. Another way to find an approximate answer with very small numbers is to use
**significant figures**.

Significant figures start at the first non-zero number, so ignore the zeros at the front, but not the ones in between. Look at the following examples:

From the first significant figure onwards, all zeros are included. It's only the zeros at the
beginning that don't count.

- Question
How many significant figures do the following numbers have?

a)

b)

c)

d)

a) has four significant figures.

b) has three significant figures.

c) has four significant figures.

d) has three significant figures.