If you want a base-10 scale, I think you only need to calculate the logarithms of 1/5 and 1/2 by hand, and the rest can be done by scaling those ratios (not to

If you want a base-10 scale, I think you only need to calculate the logarithms of 1/5 and 1/2 by hand, and the rest can be done by scaling those ratios (not to scale): | 10 | => divide by log10(1/2) : 1 | 5 | 5 | => divide by log10(1/5) : 1 |1| 4 |1| 4 | => divide by log10(1/2) : 1 |1| 2 | 2 |1| 2 | 2 | => divide by log10(1/2) : 1 |1|1|1|1|1|1|1|1|1|1|