Write the even number just before $77$$?$

 Write letter A in the box below 1st person and 3rd person.
 Write letter C in the box below 4th person.
 Write letter I in the box below 5th person.
 Write letter B in the box below 2nd person.

Tick $(✔)$ the triangle which is at the seventh position from the right.

There are _____ odd numbers before $10$.

How many tens are there in a hundred?

A spoke of an abacus can have maximum _____ beads.