Final answer:
To seat 138 students with 9 at each table, the principal would need 16 tables. The calculation is 138 ÷ 9, which equals 15.333, rounded up to the nearest whole number.
Step-by-step explanation:
The question asks how many tables are needed if a principal invites 138 students to a reward breakfast and nine students sit at each table. To find the answer, we divide the total number of students by the number of students per table. Therefore, we calculate 138 ÷ 9 to determine the number of tables needed.
The division of 138 by 9 equals 15.333. Since you cannot have a fraction of a table, we round up to the nearest whole number because we need to provide a space for every student. Hence, the principal would need 16 tables to seat all 138 students, with the last table not being completely full.