Question

How many km are in 5.6mm?

Answer 1

`5.6 xx10^-6` Km

Explanation:

If you convert to a bigger unit, the number gets smaller.
If you convert to a smaller unit the number gets bigger.

5.6mm is a really tiny distance - less than the distance across a finger nail. This is obviously a REALLY tiny fraction of a Km.

To convert mm to Km, divide by 1000 to get metres, then by 1000 again to get Km.

`5.6 div 1000 div 1000` is easier written in scientific notation as it is a tiny fraction of a Km.

`5.6 xx10^-3 xx10^-3 =5.6 xx10^-6`

1 mm is one millionth part of 1 Km.

Answer 2

`5.6 mm = 0.0000056 Km`

Explanation:

Kilometers are the largest common metric unit, while millimeters are the smallest of the common metric unit. So when changing from a small unit to a larger unit the size of the number must get smaller.

Use the chart below. It helps to visualize what is happening.

Km

      Hm

                 Dm
                              m
                                      dm
                                               cm
                                                        mm

Think of it like a stair case. When going down the stair case the size of the units gets smaller. When going up the stair case the size of the units gets larger. When going up the stair case the decimal point moves to the left, When going down the stair case the decimal point moves to the right.

Going from mm to km there are six stair steps. So the decimal must be moved six places to the left.

This gives the answer `0.0000056` or `5.6 xx 10^-6`