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.
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.
- Fifteen (Debut)
- Tween Scenes (Biggest Number)
- Step Squads (Biggest Number)
- Fifteen's Minute of Fame (Biggest Number)
- On Your Head (Biggest Number)
- Ten's Place (Biggest Number)
- Balancing Bridge (Biggest Number)
- Seventeen (Doesn't Speak)
- Loop the Loop
- Nineteen (Doesn't Speak)
- Tall Stories (Doesn't Speak)
- Flights of Fancy
- I Can Count to Twenty
- Sign of the Times
- The Lair of Shares
- The Big One
- More to Explore
- Total: 20
- 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.