Finding the Unknown Number

Learning about part-part whole relationships is essential when learning to add and subtract. When working these types of problems, the student is given a number which is the “whole”. The student is also given one other number that is one of the “parts”. The task is to find the other “part”. Students learn quickly that numbers can be split into different parts.

In the video, the teacher works through several part-part whole problems. He explains that one of the parts cannot be larger than the whole and this lets you know if you will add or subtract to find the missing part. In this worksheet, subtraction is used to find each missing part.

The worksheet provides several problems to work and the teacher explains each step he uses to solve the problem. Working part-part whole problems will improve students number sense, increase memorization of addition and subtraction facts, and that a total, or whole, can be represented by two parts.