Fifteen, or 15, is a Numberblock made of 15 blocks.

She is voiced by Teresa Gallagher.


15 is made of 10 white blocks and 5 blue blocks. She has navy limbs and pink limbs. She wears a navy 5-stair-shaped mask and 2 boots, one white, and one light blue. She likes to be a step shape (or a pixelated triangle) more than a 3-by-5 or 5-by-3 rectangle. She also splits into a group of 5 Numberblocks (1, 2, 3, 4, and 5) known as the Super Special Secret Step Squad.

Prototype Designs

Gabe Sotillo's original design of 15 is green and is male with three star-shaped eyes - one is red, one is yellow, and one is blue. He has a blue left arm, a red right arm, and yellow legs.

TSRITW's design is similar to 8, because he is ANOTHER superhero. He calls 8 his sidekick.

Arifmetix's design is navy with 3 arm-gloves with one star on each; one of which is on her head. She has 3 star eyes, one blue, one green and one blue-green.

Arifmetix's other design has 10 white blocks with a red border and 5 more blue blocks. He wears sunglasses and has 4 arms, 2 dark red, and 2 dark blue. 3 arms have gloves, the 2 red and the blue, but the gloveless blue arm can stretch. He also has darker blue lips and legs.

MDZ’s 15 is blue with 3 arms with a glove on each hand 2 at the sides and 1 on top of the head (like Arifmetix’s)

ALARM BOB OMB's design of 15 is purple and pink.



Fanart/Prototype Designs


  • 15 is the third Numberblock who is a multiple of 5.
  • 15 is the only triangular block between 11 to 20, and also an only non-prime number between 11 to 20 of the odd numbers. (5 by 3)
  • 15 is the second composite odd number. The first is 9.
  • 15 is also the first multiple of five who does not have a star on her eyes but she also doesn’t have a glove, unlike 5 and 10.
  • 15's numeral means:
    • 11 in Senary.
    • 13 in Octal.
    • 17 in Duodecimal.
    • 21 in Hexadecimal.
      • In the hexadecimal system, the numeral for 15 is F.
  • 15 is the first odd number who's voiced by Teresa Gallagher.

Numberblocks characters

Discovered Numberblocks

Zero, One, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Eleven, Twelve, Thirteen, Fourteen, Fifteen, Sixteen, Seventeen, Eighteen, Nineteen, Twenty, Twenty-One, Twenty-Two, Twenty-Five, Thirty, Forty, Fifty, Sixty, Seventy, Eighty, Ninety, One Hundred, One Thousand, Ten Thousand, One Hundred Thousand, One Million


Big Bad Square, The Terrible Twos, Octoblock, The Three Threes, Octonaughty, Step Squad, The Four Fours

Other Numberblocks

Twenty-Three, Twenty-Four, Thirty-Five, Thirty-Six, Forty-Two, Forty-Nine, Sixty-Four, Ninety-Nine, Two Hundred, Three Hundred

Irrational Numberblocks



Flapjack Snaffler, Blockzilla, Big Tum


Fluffies, Squarey, Numberblobs, Aliens, Rainbows, Flatlanders, Alphablocks


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