7 (number) facts for kids

Quick facts for kids ← 6 7 8 →
−1 0 1 2 3 4 5 6 7 8 9 → ← 0 10 20 30 40 50 60 70 80 90 →
Cardinal	seven
Ordinal	7th (seventh)
Numeral system	septenary
Factorization	prime
Prime	4th
Divisors	1, 7
Greek numeral	Ζ´
Roman numeral	VII
Roman numeral (unicode)	Ⅶ, ⅶ
Greek prefix	hepta-/hept-
Latin prefix	septua-
Binary	1112
Ternary	213
Senary	116
Octal	78
Duodecimal	712
Hexadecimal	716
Greek numeral	Z, ζ
Amharic	፯
Arabic	٧,7
Persian	٧ - هفت
Urdu
Bengali	৭
Chinese numeral	七(qi)
Devanāgarī	७ (saat)
Telugu	౭
Tamil	௭
Hebrew	ז (Zayin)
Khmer	៧
Thai	๗

The number seven is a natural number that comes after six and before eight. In Roman numerals, it is VII.

Mathematics

In mathematics, the number seven is an odd number and a prime number. It is also a Mersenne prime.

Divisibility Rule

• To test if an integer is divisible by 7 or not,

1. Take off the last digit and multiply it by 2.
2. Subtract the root number from the product .
3. Repeat the second step again and again until it is clearly that the number is divisible by 7 or not.

Example

918785

1. 5×2=10, 91878-10=91868
2. 8×2=16, 9186-16=9170
3. 0×2=0, 917-0=917
4. 7×2=14, 91-14=77

77 is divisible by 7, so the original number 918785 is also divisible by 7.

Proof: Pretend is the root number and is the last digit. Then is the whole number. If the whole number () is divisible by 7, is also a multiple of 7. And also divide 7. That proves is divisible seven, since 3 and 6 are both multiples of 3. So is also divisible by 7.

In the world

• There are seven colors in the rainbow.
• The atomic number of nitrogen.
• The number of horizontal rows of elements in the periodic table.
• Seven gates of heaven (QUR'AN 15th chapter AL-HIJR verse 44)915:44)
• Seven days in a week
• Seven seas and seven continents.
• Seven major parts of the human body (2 legs, 2 hands, trunk, neck and head)

See also

In Spanish: Siete para niños