3 is the only prime 1 less than a perfect square. - Robin Regan
is the number of spatial dimensions needed to mathematically describe a solid.
are the primary colors.
are the geometric constructions you cannot build using just a ruler and compasses: 1. You cannot trisect - divide into three equal parts - a given angle; 2. Double a cube; and 3. Square a circle.
A number is divisible by 3 when the sum of its digits can be divided by 3.
If the denominator of a rational number is not divisible by 3, then the repeating part of its decimal expansion is an integer divisible by 9. Example: 1/7 = 0.142857... has a repeating part '142857' divisible by 9. Another example with a larger recurring decimal: 1/23 = 0.0434782608695652173913... has a repeating part '0434782608695652173913' divisible by 9.
3 + 2 = log₂ 32
=

(14 - 6

5) +

5 (sum of two square roots)
= 4! / (4 x

4)
= XV/V = CL/L = MD/D
= 4 + 4 – 5 = 4³ + 4³ – 5³= 17,469 / 5,823 (this division contains all digits 1 through 9 once)
3 x 51249876 = 153749628 (the multiplication uses all 9 digits once - and so does its product!)
3 x 37 = 111
33 x 3367 = 111,111
333 x 333667 = 111,111,111
3333 x 33336667 = 111,111,111,111
33333 x 3333366667 = 111,111,111,111,111
3 x 1.5 = 3 + 1.5
3²= 3! + 3
3²= 5² - 4²
3³= 6³ - 5³ - 4³
3³= 3² + 3² + 3²
3⁴ x 425 = 34425
3 is the minimum colors needed to create camouflage patches, usually used in military compounds and vehicles. - posted by George Pantazis
A 3 x 3 alphamagic square is a magic square for which the number of letters in the word for each number generates another magic square, for instance:

5	22	18
28	15	2
12	8	25

five (4)	twenty-two (9)	eighteen (8)
twenty-eight (11)	fifteen (7)	two (3)
twelve (6)	eight (5)	twenty-five (10)

A 3 x 6 rectangle has an area equal to its perimeter.
In one gram of water the number of molecules is about:
3.3 x 10²² = 33000000000000000000000
The balanced ternary base, is a numeral system which uses 3 values or digits: -1, 0, and 1. It works as follows (in the example, the symbol 1 denotes the digit -1):

Decimal	-6	-5	-4	-3	-2	-1	0	1	2	3	4	5	6	7
Balanced ternary	110	111	11	10	11	1	0	1	11	10	11	111	110	111

Ternary or base-3 numbers can be converted to balanced ternary notation by adding 1111... with carry, then subtracting 1111... without borrow. For instance:
021₃ + 111₃ = 202₃, 202₃ - 111₃ = 111_3(bal) = 7₁₀
This non-standard positional numeral system is easily represented as electronic signals, as potential can either be negative, neutral, or positive (comparison logic). The balance ternary system is also useful to solve the classical 2-pan balance puzzle.
The letters A, F, H, K, N, Y and Z are made up with 3 lines.
In SMS language <3 font=""> means 'I love you', and <333 font="">, 'I love you so much'.
3 hundred millions of Indians live with less than 1 dollar per day (2004).
Non-paternity rates: statistically, one in three men who ask for paternity test turn out not to be the biological parent.
An octopus has 3 hearts.
The number 3 symbolizes the principle of growth. In Guangdong province, China, three is associated with living or giving birth.
"Sanqing" (also known as "Sanxing" or "Sancai"), in the Mystical Numbers of Taoism, represents the number 3 and symbolizes the Three Luminaries: Sun, Moon, Stars. It also defines the concept of "Heaven, Mankind, Earth" as well as "Upper, Centre, Lower".
Deep thought: "There are 3 kinds of people: those who can count and those who can't".
Riddle 1: Spell 'mousetrap' in 3 letters...
Answer: C-A-T.
Riddle 2: Spell 'water' in 3 letters...
Answer: H-2-O.
Joke: Chuck Norris once won a game of Connect Four in 3 moves!

If you’re a Simpsons fan, then you problably know about “Blinky”, the three-eyed fish found near the nuclear plant where Homer Simpson was working. As it turns out, the Simpsons were right yet again, as fishermen in Córdoba, Argentina caught a three-eyed wolf fish in a reservoir fed by a local nuclear power plan! (Fri, Oct 28, 2011)
Er Lang Shen

In the taoist mythology, Erlang Shen (二郎神), or Erlang is a Chinese God with a third truth-seeing eye in the middle of his forehead.
The French sentence 'un bonhomme haut comme trois pommes' (a 3-apple-tall fellow) and the German sentence 'ein Kerlchen drei Käse hoch' (a 3-cheese-tall fellow) mean both a pint-sized guy/child.
"Les fourmis, chacune d'elles ressemble au chiffre 3. Et il y en a! Il y en a 333333333333... jusqu'à l'infini" (Jules Renard, 'Histoires naturelles').
Translation: "The ants. Each of them resembles a figure 3. That's, it. There are 333333333333 to infinity".
'Bookkeeper' and 'bookkeeping' are the only words in the English language with three consecutive double letters.
The most common three-letter words in order of frequency are: the, and, for, are, but, not, you, all, any, can, had, her, was, one, our, out, day, get, has, him, his, how, man, new, now, old, see, two, way, who, boy, did, its, let, put, say, she, too, use.
The name "Mitsubishi" (三菱) consists of two parts: "mitsu" meaning 'three' and "bishi" meaning 'water caltrop', and hence 'rhombus', which is reflected in the company's famous logo (it is also translated as 'three diamonds'). Other Japanese family names containing the number 3: Mitsudani, Mitsugi, Mitsui, Mitsuhashi, Mitsude, Mitsuishi, Mitsumura, Mitsubori, Mitsumata, Mitsuyama, Mitsuzawa, Mitsuya, Mitsukuchi, Mitsukyou, Mitsuboshi, Mitsuzima, Mitsue, Mitsuike, Mitsuaichou, Mitsubuchi, Mitsuse, Mitsuyanagi, Mitsumachi, Mitsukunugi, Mitsuwa, Mitsuzaku, Mitsumatsu, Mitsuhuzi, Mitsuduka, Mitsuwari.

THREE in different languages (© G. Sarcone)
(Old English thrīe)

Indo-european | *TREYES, *TISORES, *TRI |
Sanskrit |

TRÎ |

Italian tre; French trois; Spanish and Catalan tres; Provençal trei, tres; Portuguese três; Romanian trei; Romansh trais; Sardinian très.

Old Celtic | TRI |

Breton tri (m), teir (f); Welsh tri (m), tair (f); Irish trí (m), teoir (f, old Irish), triúir (people).

Old Germanic | THRIJIZ |

Dutch drie; German drei; Danish, Norwegian, and Swedish tre; Icelandic þrír.

Old Slavic | TRIJE, TRI |

Russian три tri; Czech tři; Slovenian trí; Polish trzy.

Proto Indo-Iranian | *TRAYAS |

Persian سه se; Hindi तीन t̪iːn.

Evolution from 'seal script' to modern sinograph 三 :
Old Chinese (pron.) | sâm |

Chinese 三 sān. The sinograph 叁 is used as a replacement for sān on legal and financial documents to prevent fraud.

Proto-Semitic | *SALATh |
Semitic root | Th-L-Th |
Ancient Egyptian [ḫmt'-] khemet; Akkadian shalash; Punic shlosht.

Arabic ثلاثة thalathâ; Hebrew שלושה shlôshah; Maltese: tlieta; Amharic sost.

More languages
Magyar három.
Turkish üç.
Mayan oxi'.
Nahuatl ēyi.
Suomi kolme.
Zulu (ku)thathu.

HIDDEN ROOTS
The roots of the word three are hidden in the following words: contest, detest, obtest, protest, sesterce, sitar, teapoy, tercet, tertian, tern, terpolymer, test, testament, testicle, testify, testimony, trammel, travel, trefoil, trench, trephine, trey, triad, triangle, triathlon, tribe, trio, triple, triplex, trine, trinity, trimurti, trivial, triumvir, trocar, troika; third, thrice. In French: travail, treillis, trémail. In Spanish: terliz, trabajo.

15 fun ways of practising the Past Perfect

1. Fairytale dominoes This is a game from Intermediate Communication Games that can easily be played without access to the book. Students continue a story by choosing from pictures that they have spread out on the table in front of them, continuing until they bring the story to a conclusion with the very last picture. To [...]

1. Fairytale dominoes
This is a game from Intermediate Communication Games that can easily be played without access to the book. Students continue a story by choosing from pictures that they have spread out on the table in front of them, continuing until they bring the story to a conclusion with the very last picture. To make the use of Past Perfect higher, allow them to add pictures to earlier in the story with phrases like “By the time he arrived back at the castle, the witch had already kidnapped the princess”. You can play the same game with other kinds of story such as murders and spy stories (crime vocabulary), science fiction or love stories. If you can’t find suitable pictures, students can play the same game with relevant words on cut up pieces of paper.
2. Alibi game
Half the class are suspects for the murder of someone in the school, and the other half are their alibis. In pairs, they have to create the stories of what they were doing elsewhere at the time of the murder. They are then questioned separately, and the pair with the most differences between their stories are the guilty ones. This is one of the all time classic TEFL games and gets students who are usually shy or uninvolved speaking much more than usual.
3. Business English alibi game
With some careful preparation, the concept of the alibi game can be extended into other fields such as Business English. Prepare slips of paper with typical business daily tasks such as “send a fax”. Students set them out to make an imaginary business day and then try to memorize their own day. Another student then tests them on the order of the events with questions like “Had you already finished lunch when you started gossiping?” or “How many things had you achieved before the meeting with your boss started?” You can also add the Past Continuous by allowing them to place some of the slips of paper vertically to represent things that lasted a longer time during which other things happened (slips of paper placed next to them horizontally).
4. Past Perfect Kim’s Game
Another game that can be played with the same pieces of paper as the Business English Alibi game above is for one student to move around the pieces of paper showing the sequence of events in the day and for the other person to spot and explain the changes, e.g. “Now it says I had already polished my shoes when I put them on, but actually I put my shoes on and then polished them”.

Impossible folding paper problem

ORDINAL NUMBERS

BIG NUMBERS

NUMBERS

JAPAN, the strange country...

NUMBERS...

CE - Clear Everything

Motor coordination...

Mathematical Symbols

for teachers

15 fun ways of practising the Past Perfect

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