Working with Subtraction Input-Output Tables

Instructor: Jaimee Arnold

Jaimee has worked in elementary school and has her Master's +30.

In this lesson, you'll find out what an input-output table is and how to use one. You'll also learn about the vocabulary used with the table and how to complete a subtraction input/output table.

Understanding an Input-Output Table

An input-output table is a table that shows the relationship between sets of numbers that always follow the same rule. Input-output tables can be very complex (with several math operations) or simple (with just one math operation). In some problems, the rule for the input-output table is given, while in other problems, you'll need to figure out the math rule for the input-output table. In this lesson, we will focus on working with subtraction to solve the input-output table.

The rule for the input-output table must be the same for all the number sets that are included in the table. If the rule does not work for each set of numbers, it is not the correct rule for the table.

Math Vocabulary

Before you learn how to solve the input-output table, you'll need to learn some new vocabulary words.

  • Input-output table: This is the actual table that has the sets of numbers on it. This table is also known as a function table.
  • Input is the number in the first column of the table. If given a rule, this is the number that you start with. You can also use this number to figure out what the rule is if it is not given.
  • Output is the end number or the answer to the math equation.
  • The rule is the math operation that needs to be followed to get the correct sets of numbers for your input-output table. Take a look at the illustration to see how the table is set up.

This is what an imput output table looks like.

Using the Rule

When you first look at an input-output table, you'll notice that the rule is usually at the top of the table, as shown in the example problem below. In this case, the rule is 'subtract 200.'

Input Output Table for subtraction 200

The rule is very important and is the same for each row in the table. Because the rule is so important, the first thing you need to do is circle it. Next, look at the first row in your table. Take the first input number and subtract the rule. In this example, your number sentence would be: 900 - 200 = ? The answer to this problem will be the output number.

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