Round 12.65 to 3 significant figures Step by Step

Step by step

The question

Question: round 12.65 to 3 significant figures.

Round 12.65 to 3 significant figures

1 Find the first significant figure

The first significant figure is the first digit that is not 0.

In 12.65, it is 1.

= 12.65

significant figures: counted from

the first digit that is not 0

2 Count the figures

We count 3 figures from there: 1, 2, 6.

The 3rd figure, 6, is in the tenths place.

So we round to the nearest tenth.

= 3rd figure 6 → the tenths place

3 Look at the next digit

Now we look at the next digit to the right.

It is 5.

5 or more: we round up.

4 or less: we round down.

5 is 5 or more, so we round up.

= 5 is 5 or more → round up

5 or more → up: digit + 1

4 or less → down: digit stays

4 See it on a number line

12.65 is exactly halfway.

Halfway rounds up, to 12.7.

5 Keep the size

We stop after the 3rd figure.

So 12.65 is about 12.7.

= 12.65 ≈ 12.7

So 12.65 to 3 significant figures is 12.7.

6 Check

Let's check.

12.7 has 3 significant figures: 1, 2, 7.

12.7: figures 1, 2, 7 → 3 s.f.

And it is close to 12.65.

So the answer is right!

12.65 ≈ 12.7: the same size

Let's look back.

First: find the first significant figure.

Then: count the figures.

Then: look at the next digit.

Then: see it on a number line.

Then: keep the size.

Last: check.

Answer