Subtraction
Remember, the verbs in a sentence are responsible for making questions.
In a mathematical equation, the equal sign (=) is the verb.
The To Be Verb
Look at this simple equation:
12 – 3 = 9 “twelve minus three is nine”
On the right side of the equal sign, there is just one number (9). This side of the equal sign is singular with just one answer, right?
On the left side of the equal sign, there are two numbers (12 minus 3). That makes it plural, right? Not in math.
The math operation, in this example subtraction, is a singular phrase. In math, 12 – 3 is a single idea. Teachers and students of English grammar can think of the chunk of language of 12 – 3 as the subject of the sentence. In math, this subject is always singular.
Since the subject is singular, the verb must be in singular form, too. The “to be” form “is” refers to 3rd-person singular grammar. This is the grammar of basic operations in math. This is why we use “is” for the equal sign no matter how many numbers or operations are on a side.
Now we can understand how to make a question about a math equation.
How does English form a question with a “to be” verb when that verb is “is”?
Let’s review the Yes/No questions.
12 – 3 = 9 “twelve minus three is nine”
“Twelve minus three” is the subject. “Is” is the verb. They change places.
“Is twelve minus three nine?”
The answer can only be yes or no. This is called a Yes/No question.
Your Turn — Practice yes/no questions with “is” for the equal sign
For the equal sign, we have the following “is” phrases to say the equal sign:
- is equal to
- is equivalent to
- is the same as
- is the same amount as
- is the same value as
Remember that the “is” phrases get separated when making yes/no questions.
For example,
12 – 3 = 9 the questions are:
“Is 12 minus 3 equal to 9?”
“Is 12 minus 3 equivalent to 9?”
“Is 12 minus 3 the same as 9?”
“Is 12 minus 3 the same amount as 9?”
“Is 12 minus 3 the same value as 9?”
Your Turn — Practice yes/no questions with “is” phrases
The Other (non-To Be) Verbs
The equal sign works as the verb in mathematical sentences. Do you remember the ways to say the equal sign without using the “to be” verb “is”?
24 – 7 = 17 can be said as, “24 minus 7 equals 17″ or “24 minus 7 makes 17.
Notice the final -s at the end of both of the words “equal” and “make” used for the equal sign. The final -s identifies the verb as a 3rd-person singular verb as we saw with the word “is”. Let’s learn about the “equals” verb first.
“equals”
How can we make a yes/no question without the “to be” verb “is”?
Let’s look at the equation.
24 – 7 = 17 “twenty-four minus seven equals seventeen”
We must use the 3rd-person singular verb grammar rule to make a yes/no question. We begin the sentence with “does” and drop the final -s from the word “equals”.
For example,
24 – 7 = 17 The question is, “does 24 minus 7 equal 17?”
17 – 14 = 3 The question is, “does 17 minus 14 equal 3?
Your Turn — Practice yes/no questions for “equals”
“makes”
The word makes for the equal sign also uses the final -s for the 3rd person singular verb form. The way to make a yes/no question for “makes” is the same as above for “equals”.
For example,
5 – 3 = 2 The question is, “does 5 take away 3 make 2″?
23 – 19 = 4 The question is, “does 23 and 19 make 4?
Your Turn — Practice yes/no questions for “makes”
Summary
- The equal sign is the verb in mathematical equations
- If the equal sign is said with “is”, the question formation follows the “to be” grammar pattern.
- If the equal sign is said with a non-to be verb, the question formation follows the grammar pattern that uses “does”.
- Yes/No sentences are used to ask if an answer is correct.
