A monster with a big hairy tummy who loves puzzles? find out who is in Big Tum's tum.
The Numberblocks 1-10 are climbing up Blocky Mountain. Seven says they might see Big Tum, a big hairy monster with a big hairy tum who loves to solve puzzles. Then a cold wind blows. The scene fogs and Big Tum appears.
Eight asks is one of them is missing. The Numberblocks call out their number in order from 1 to 10. Four appears to be swallowed by Big Tum. Five asks is Four is okay. Four says it's all warm and snuggly in Big Tum's tum.
One and Nine visit an igloo and hears Big Tum's "yum yum!" Nine is changed into Three, who says she was Nine and Big Tum swallowed some of his blocks. She doesn't know how many were swallowed, so One draws Nine on the ice wall.
9 - ? = 3
Who's missing? One grabs some ice blocks. She counts six as she puts each one on Three. It's Six who was swallowed by Big Tum. Big Tum spits out Six who adds with Three to make Nine.
One asks where the others went. Two, Three, Four, Five, Six, Seven, and Ten are riding Eight tobogganing in the igloo. The scene fogs, and when it clears up, One, Two, Three, and Four are turned into snowblocks. Big Tum returns and says he swallowed the real One, Two, Three, and Four together.
1 + 2 + 3 + 4 = ?
Nine adds up Snowblocks 1-4 together. Ten counts the ten snowblocks altogether, so Ten is the swallowed Numberblock. She is spat out and separated into 1-4. Ten asks Big Tum if they can all come in until it stops snowing. All the Numberblocks are then swallowed by Big Tum. At the end, Big Tum eats and swallows the camera.
- A missing addend is dubbed as the word 'Yum!' by Big Tum.
- This episode teaches basic algebra.
- This is the second time a character made an interaction with the viewers. The first was Three Little Pigs.
- This is also the second time the fourth wall is broken.
- Eight is one block tall while sleighing. This marks the first time a Numberblock is arranged with blocks on their back.
- It's possible that Numberblock Fifty-Five was inside Big Tum while the latter swallows the camera at the end, due to the fact that Big Tum let all the Numberblocks in his tum.
- The image of One, Two, Three, and Four as snowblocks is used as an exclusive winter-themed wiki background.