[pdurrant]

Originally Posted by Javed

I tipped the wrong one out last time. OK. I think I have it now.......

(no peeping Geoff!)

Spoiler:

Pour from the 16 pint container into the 7 pint container until full.

Pour from that 7 pint container into the 3 pint container until the 3pint container is fulll.

Discard what is in the 7.

Pour the remainder of the 3 pint container which is 3 pints back into the 16pint container.

Pour from the 16pint container into the 7 pint container until full.

Pour from the 7 pint container into the 3 pint container until full.

Discard what is in the 7 pint container.

Pour the remainder of the 3 pint container into the 16 pint container.

The 16 pint container now has 8 pints (one gallon).

Alas, no. Your method gives you a little less than a gallon, as the two gallon container starts off "very nearly full" not full.

Have another go!