Two Step Conversions

For harder conversions, convent to the 10^2 prefix first.

Eg.  0.040km  into  cm
km→m→cm
0.040km    1000m     *   100cm  4000cm
                    1 km               1  m

Eg.   3400µs    into  hs.
µs→s→hs
3400µs  *     1      s       *    1        hs 
                    10^6 µs           10^2  s

Eg.  Convent  12 mm   into kilometres.
mm→m→km
12mm   *    1      km       *      1         m         = 12*10^-5  km
                   1000  m               1000   mm


The advantage of including unit symbols now becomes evident we set up the conversion factors.

1       m                 1      km
1000mm               1000 m

Eg. convert   15mg  into decigrams.
mg→g→dg
1000mg=1g            1g=10dg

15mg  *    1           g          *     10   dg 
                  1000 mg                 1      g

Derived Quantity  Conversions.
A derived quantity is when there is more than one is bace whit in a single quantity.
Eg. convert the rate 8km   into cm/s
                                  ms

Two seqatate unit conversions are needed.

1. km→m→cm

Using 1 km = 1000 m and 100 cm = 1 m

1. ms→s

Using 1000 ms = 1 s

8  km  *  100  m  *  100 cm  *  1000 ms  = 8*10^8 cm/s
    ms       1    km      1     m        1        s