Scaling Units
The
table below gives a rough idea of the units to use when setting up numeric
scales for graphs. As you gain
experience in setting up numeric scales, you may decide that a situation
requires smaller units or larger units than those given by this table.
The
data range is the maximum data value minus the minimum data value. The classes for

Units 
0.07 to 0.14 
0.01 
0.14 to 0.30 
0.02 
0.30 to 0.70 
0.05 
0.7 to 1.4 
0.1 
1.4 to 3.0 
0.2 
3.0 to 7.0 
0.5 
7 to 14 
1 
14 to 30 
2 
30 to 70 
5 
70 to 140 
10 
140 to 300 
20 
300 to 700 
50 
700 to 1400 
100 
1400 to 3000 
200 
3000 to 7000 
500 
0.7 x 10^{ n} to 1.4 x 10^{ n} 
1 x 10^{ n–1} 
1.4 x 10^{
n} to 3.0 x 10^{ n} 
2 x 10^{
n–1} 
3.0 x 10^{
n} to 7.0 x 10^{ n} 
5 x 10^{
n–1} 