16 x 8 x 10 = 1280 cubic inches 1280/231 = 5.54 gallons
That looks like a 45 gallon tank.
Here is a handy calculator:
http://www.angelfish.net/tankvolcalc.php
3ft x 1ft x 16in = 113.27 liters = 29.92 US gallons
If your dimensions are in inches, the aquarium can hold up to 24.94 gallons.
A tank this size can hold a maximum of about 5.6 US gallons of water.
Over 8 millions gallons
1.33 gallonsAssuming that you mean 36cm x 14cm x 12cm, multiplying these together gives 6048 cm3. Converting this to dm3 (which is in other words, 1 litre) by dividing by 1000 gives 6.048. Then, by dividing by 4.55 you get 1.3292307 etc. which rounds up to 1.33 to three significant figures.
694.4days
Fill a gallon bucket, timing how long it takes to do so. Then fill your hot tub using the same source... example: if you filled the bucket with a hose, then fill the tub using the same hose. Then time how long it takes to fill the tub and divide the time it takes to fill the tub by the time it takes to fill the bucket and then you know how many gallons it is.
A very very large one. The kind of thing you would see several of at a National or Public Aquarium that is open to the fee paying public.
About 240 US gallons
That would be a standard 29 gallon aquarium
This aquarium can hold a maximum of 10 gallons of water.
100 liters is 22 Imperial gallons.
About 10 gallons.
Assuming the only thing in the aquarium is water, this tank could hold up to 19.8 gallons of water.
If filled to the top it would hold 6.34 gallons.
If you mean inches, the maximum water capacity is 19.95 gallons.
Over 8 millions gallons
There are about 33.7 gallons in a 3' by 1' by 1'6" aquarium.
An aquarium with a capacity of 5.2 US gallons has a volume of 1,201.2 cubic inches.
The packaging or booklet usually gives the volume of the tank, but if it does not, fill the aquarium one gallon at a time (or if it is large, 2-5 gallons at a time) until it is filled. The number of gallons that is put in the aquarium is the number of gallons of water the tank holds.