A curiosity about Bitcoin you might not know.

If you are at the last block of the current Epoch and look behind, the subsidy per block equals the percentage of the total supply mined during that Epoch and the percentage of total supply that still need to be mined.

Example:

we are at Epoch 4, the subsidy is 6.25 BTC per block.

At block 840,000 we'll start a new Epoch with a new halving.

The total bitcoin mined during Epoch 4 will be 6.25% of the total supply, and an additional 6.25% will remain to be mined.