Here are the answers and Cheats to Escape Room: Math Doors Door 81. If you need help with other levels check our Escape Room Math Doors Page.
Hint – Observe the rounding off closely.
Solution – 7 1/2 of i.e 2.5 is 3. 1/3 of 10 is 4 So, rounding off is done with the higher number. 20/3=6.66=7