Number
30
- Positive
- Even
- Composite
- 2 digits
30 is an even 2-digit integer and a composite number. It has 8 divisors and a digital root of 3.
The canonical address for this page is /30.
Number properties
ParityEvendivisible by 2
SignPositive
PrimalityComposite
Absolute value30
Digit count2
Digit sum3
Digital root3repeated digit sum
PalindromicNoreads differently backwards
Happy numberNosquared-digit sums reach 1
Harshad numberYesdivisible by its own digit sum
Factors & divisors
Prime factorisation2 × 3 × 5
Distinct prime factors32, 3, 5
Number of divisors8
Sum of divisors σ(n)72
Aliquot sum42sum of the proper divisors
ClassificationAbundantthe aliquot sum exceeds the number
Euler's totient φ(n)8integers below n that share no factor with it
SquarefreeYesno repeated prime factor
All divisors1, 2, 3, 5, 6, 10, 15, 308 in total
Arithmetic
Representations
Decimal30
Binary111105 bits
Octal36
Hexadecimal1E
Base 36U
Roman numeralXXX
In wordsthirty
Ordinalthirtieth
Scientific notation3 × 10^1
Engineering notation30
Nearest landmarks
Powers & multiples
30 to the power 2900
30 to the power 327,000
30 to the power 4810,000
30 to the power 524,300,000
First ten multiples30, 60, 90, 120, 150, 180, 210, 240, 270, 300
Powers of twoBetween 2^4 (16) and 2^5 (32)
Divisibility tests
Divisible by 2Yes
Divisible by 3Yes
Divisible by 4No, remainder 2
Divisible by 5Yes
Divisible by 6Yes
Divisible by 7No, remainder 2
Divisible by 8No, remainder 6
Divisible by 9No, remainder 3
Divisible by 10Yes
Divisible by 11No, remainder 8
Divisible by 12No, remainder 6
Divisible by 100No, remainder 30
Collatz (3n + 1) trajectory
Steps to reach 118the total stopping time
Reaches 1Yesthe Collatz conjecture says every positive integer does, but it is unproven
First steps30 → 15 → 46 → 23 → 70 → 35 → 106 → 53 → 160 → 80 → …
Last steps… → 5 → 16 → 8 → 4 → 2 → 1
As a percentage & fraction
As a percentage3,000%
30% as a decimal0.3
30% of 10030
30% of 1,000300
As a fraction of 10030/100
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Derived from 30
Other readings
Also reads as
#000030 (colour)
- #000030
- Blue
- Dark
- Nearest: Black
#000030 is a blue with RGB values 0, 0, 48 and HSL 240°, 100%, 9%. It is a dark colour, so white text on it reaches 20.1:1 contrast (AAA for normal text). The nearest named colour is Black.
Colour values
#000030#000030
HEX#000030
RGBrgb(0, 0, 48)
RGB (0–1)0, 0, 0.1882
RGB percentages0%, 0%, 18.8%
HSLhsl(240, 100%, 9.4%)
HSV / HSBhsv(240, 100%, 18.8%)
CMYK100%, 100%, 0%, 81.2%≈naive device-independent conversion; real print needs an ICC profile
24-bit integer48
CSS custom property--colour: #000030;
Brightness & contrast
Relative luminance0.00213WCAG 2.x, 0 is black and 1 is white
Perceived brightness16.2 of 255ITU-R BT.601 weighting
Light or darkDark
Best text colour on this backgroundWhitecontrast 20.14:1
Contrast with white20.14:1WCAG normal text: AAA
Contrast with black1.04:1WCAG normal text: Fail
Greyscale equivalent#030303
Inverted#FFFFCF
Colour vision & accessibility
Distinguishable without hueYesnever rely on hue alone to carry meaning
Contrast with white, large text20.14:1WCAG large text: AAA
Contrast with black, large text1.04:1WCAG large text: Fail
Named colours
Hue familyblue
CSS keyword usableNo exact keyword
Colour harmonies
Complementary#303000
Analogous#001830, #180030
Triadic#300000, #003000
Split complementary#301800, #183000
Tetradic#300018, #303000, #003018
Tints, shades & saturation
Channel breakdown
R0
G0
B48
Red0 (0%)
Green0 (0%)
Blue48 (18.8%)
Hue240°
Saturation (HSL)100%
Lightness9.41%
Dominant channelBlue
Hex per channelR 00 · G 00 · B 30
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Harmonies
Similar named colours
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