9 is sneezing. 1 asks him what's wrong. 9 tells her that every time he sneezes, he always gets 1 smaller. He sneezes out his middle block, turning into 8. The 1's wave at each other as the other 1 merges with 8 to make 9. 9 wonders why he can't get 1 bigger. 1 tells 9 that maybe he can asks him to stand vertical as they add up.
9 + 1 = 10
10 goes to the magic mirror to duplicate herself.
10 - 1 = 9
9 tells 10 she's 1 bigger. 1 asks 10 why she has a number 1 on top. In a song, 10 explains to 1 she's made of 10 blocks and she's one 10. Then 1 asks 10 what the round thing is next to the 1. 10 says it's called a 0, which means 10 has a number 1 in the tens column. The song continues.
Notes
Song: I'm A Ten Block
Numberblocks 1-10 have their own tree:
1: a pine tree
2: a tree with two blocks
3: a triangular tree
4: a square tree
5: a star tree
6: a dice tree
7: a rainbow tree
8: a tree with eight arms
9: a tree with nine blocks arranged in a square
10: a tree with ten fruits
This is the first time 5, 6, and 7 meet 9.
This is the first time 9 is arranged vertically.
2, 3, 5, and 7 stay vertical in this episode.
Coincidentally, they are prime Numberblocks.
This is the first time 10 is arranged in a triangle (1+2+3+4).
The instrumental version of the song can be heard in 10's games in the game Numberblocks Make & Play.
Errors
When 9 sneezes into 8, he has only 4 normal limbs.
When 4 separates his blocks, his mouth is missing.
When Ten arranges herself into her 2x5 form for the first time, her limbs are gray and her red sides and white for a split second.