How many gallons of water will fit in a 76x80x9 container?

Answer 1

It would depend upon the units you are using for the length. Feet? Inches?

Here are both:

1) 76" x 80" x 9" container is 54720 cubic inches, which is 236.88 gallons.

2) 76 ft x 80 ft x 9 ft is (a huge pool?) 54720 cubic feet, which is 409,334 gallons.

(There are 1728 cubic inches in a cubic foot, so we could have multiplied. But the lost significant digits in the calculations mean that 236.88 x 1728 is just 409,328 gallons.)