labelsKMB:

labelsKMG2:

labelsKMG2 together with labelsKMB (legacy, violates standards):

labelsKMG2 with yValueFormatter:

labelsKMB with very small numbers:

labelsKMG2 with very small numbers:

labelsKMG2 together with labelsKMB (legacy, violates standards) with very small numbers:

The curves are exponentials. Zooming in should reveal each of the 'K', 'M', 'B', etc. labels.