1Kg bag from Morrisons 25p covers a huge area, snip off corner then go along your block paving & path edges pouring out a thin trickle, the best part about it is, non harmful to pets or wildlife, rain helps to wash it into the ground rather than diluting as with other weedkillers.
Best of all it works & lasts a long time,
Can be used along borders if you are careful, pour onto the centre of Dandelions & watch them wilt
Common sense is not so common
A brain is as strong as it's weakest think