IMAS 2020 — Upper Primary Grades 5–6 — Round 1 Question 18

There are 43 pearls with a hole in the center that are to be stringed together using a thread such that the thread will form the letters "I", "M", "A", and "S", as shown in the figure below. If each pearl can only be passed through once by the thread, how many from the four letters cannot be done?









I:

M:

A:

S: