Logical Riddle: How Will You Measure 6 Gallons of Water?

Fill up the 7 gallon jug completely.

Now pour as much of the 7 gallons as you can into the 4 gallon jug.

You should have 3 gallons in the 7 gallon jug.

Dump out the 4 gallon jug, pour the 3 gallons from the 7 gallon jug into the 4 gallon container.

Finally, fill up the 7 gallon jug completely and pour what you can, 1 gallon, into the 4 gallon jug until it is full.

Taking 1 gallon from seven gallons leaves 6 gallons.