How many meters are in 2.5 kilometers? Step by Step

Step by step

The question

Question: change 2.5 kilometers into meters.

2.5 km = ? m

There are four choices.

First we solve it, the normal way.

Then we pick.

1 Find the link

1 kilometer is 1000 meters.

1 km = 1000 m

2 Make the unit fraction

We want meters, so meters go on top.

We have kilometers, so kilometers go at the bottom.

Top and bottom are the same amount.

So the fraction is 1, and times 1 keeps the size.

1000 m1 km = 1

Careful!

Not upside down.

Then the kilometers would not cross out.

Careful: not 2.5 km × 1 km1000 m ✗

3 Multiply

We multiply 2.5 kilometers by the fraction.

2.5 km = 2.5 km × 1000 m1 km

Kilometers on top and at the bottom cancel, like numbers.

Cross them out.

Meters are left.

What is left: 2.5 times 1000.

= 2.5 × 1000 m

2.5 times 1000 is 2500.

So 2.5 kilometers is 2500 meters.

= 2500 m

4 Check

Does it make sense?

Meters are smaller than kilometers.

So we need more of them.

2500 is more than 2.5.

Yes.

m smaller than km → more: 2500 > 2.5

And back the other way: 2500 divided by 1000 = 2.5.

We get 2.5 kilometers again.

So the answer is right!

back: 2500 ÷ 1000 = 2.5

5 Pick the choice

Our answer is 2.5 km = 2500 m.

That is choice D.

D) 2500

6 Why not the others

A is 0.0025.

Wrong: divided by 1,000 instead of multiplying.

A) 0.0025 ✗ divided by 1,000 instead of multiplying

B is 25.

Wrong: moved the point 1 place: a kilometer is 1,000 meters.

B) 25 ✗ moved the point 1 place: a kilometer is 1,000 meters

C is 250.

Wrong: moved the point 2 places: a kilometer is 1,000 meters.

C) 250 ✗ moved the point 2 places: a kilometer is 1,000 meters

Let's look back.

First: find the link.

Then: make the unit fraction.

Then: multiply.

Then: check.

Then: pick the choice.

Last: why not the others.

Answer