The second effect is gained from having something cost 800V but only allowing you to buy packs of 1000V.
Then you end up with 200V burning in your pocket that you can’t spend. So you buy another 1000V, spend another 800V and now you’re stuck with 400V.
So instead of spending 7.5 euro for 800V you spent 40 euro for 4000V to get to an even 0V left.
The second effect is gained from having something cost 800V but only allowing you to buy packs of 1000V.
Then you end up with 200V burning in your pocket that you can’t spend. So you buy another 1000V, spend another 800V and now you’re stuck with 400V.
So instead of spending 7.5 euro for 800V you spent 40 euro for 4000V to get to an even 0V left.