Is it 2 foot or 2 feet?
You're absolutely right about 'five foot tall'; if you're talking to someone or writing and don't need to be formal, saying that you're 'five foot tall' is fine. However, to say you are 'five feet tall' is correct and is probably safer when you're writing in English.One Foot, Two Feet — Foot is Singular, Feet is Plural

Feet is simply the plural form of foot — for both meanings. So if you're talking about only one, you say “foot.” If more than one, “feet.”“Foot” refers to a single unit of measurement whereas “feet” is its plural alternative. The abbreviation used for foot or feet is ft and the symbol used is '. For example, a bag that is 1 foot long can be written as 1 ft or 1'.

Do you say 3 feet or 3 foot : "Foot is a singular noun," Peter said as he used the 25-foot air hose at Curly's Soonerco to inflate his tires. "The plural of 'foot' is 'feet,' and the hose is 25 feet long.

Is it 10 feet or 10 feet

However, if the length is used as an adjective modifying another noun, the singular is used, eg “the 10-foot pole.” If it is announcing the length of something, the plural is used, eg, “the pole is 10 feet long.” A minor rearrangement of the sentence may change which form is used. The 10-foot pole is 10 feet long.

Is it 6 feet or foot : If you're talking about the height of a person, it's six feet. However, if you're adding an additional number, like 6′2 for example, You would say “He/She is six-foot two.”

It's important to note that the singular form "foot" is used when the height is mentioned alone, while the plural form "feet" is used when there is an additional number mentioned.

You always use foot as the plural in front of another noun. For example, if a gap is twenty feet wide, you refer to it as a 'twenty foot gap'. Don't refer to it as a 'twenty feet gap'. The prison was enclosed by a forty foot wall.

Is it 8 foot or 8 feet

The second form (8 feet tall) would also be the best form to use with the verb 'to be'. The statue is 8 feet tall. The singular form 'foot' can more readily be substituted for the plural 'feet' than 'feet' can be substituted for 'foot', but it is not a standard usage to do so. It sounds colloquial.If you're talking about the height of a person, it's six feet. However, if you're adding an additional number, like 6′2 for example, You would say “He/She is six-foot two.”Which one is correct 40 is plural so feet is most grammatically correct. 40 foot is southern American colloquial so I won't quibble.