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# Can you think of examples where 2 + 2 does NOT equal 4?

Like, for example, 2 gallons plus 2 quarts does NOT equal 4 gallons.

### 5 Answers

- Jeffrey KLv 72 months ago
You can not add different units together. It's not that 2+2 doesn't equal 4. It is just that gallons plus quarts can not be added.

Here are some mathematical instances when 2+2 is not 4.In base 3: 2+2 = 11In base 4: 2+2 = 10If two vectors of length 2 are added, the sum will be less than 4.

In algebra, 2X + 2 is not 4 or 4X. They can not be added.

In Relativity, a speed of 2 hundred thousand km per sec plus 2 hundred thousand km per sec is not 4 hundred thousand km per sec. It is less. You must use the Relativistic velocity addition formula.

- JimLv 72 months ago
A change in number base, such as base 3 or base 4

A change in units like 2 gals + 2 qts

A change in systems such as 2 gals + 2 liters

In human terms such as 2 couples having babies.

Etc. for like a million (exaggeration) different ways.

- UserLv 72 months ago
Certainly.

You're using different units, which is sort of cheating.

Another way of doing this is adding groups, collective nouns and the like.

Examples:

Consider: 2 flocks of birds (of the same species) combine with 2 flocks of birds (again: of the same species)

2 flocks + 2 flocks = 1 flock

There is a merger between two companies, the result being the forming of a new company

1 company + 1 company = 1 company

One company purchases another company and integrates it into the parent company.

company A + company B = company A

etc.

(many variations on the theme)

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- billrussell42Lv 72 months ago
your example is bad, you cannot add unlike terms.

8 qt + 2 qt = 10 qt

vectors are a real example. A force of 2 N east plus a force of 2 E add to 2.8 N NE

then there is the classic, where everything is rounded to 1 place

2.4+2.4 = 4.8 when rounded is

2 + 2 = 5

or speeds approaching light speed.

relativistic speed additionS = (v+u)/(1+vu/c²)

let u and v be 2e8 m/s

S = 4e8 / (1 + 4/9) = 2.7 m/s

so 2e8 plus 2e8 = 2.7e8 m/s

of course, non of these are actually 2 + 2 ≠ 4