Answer: In general, look for key words like "is" and "are," or "be." These become the equal sign in the equation.
Other key words to help decide which operation to use:
"And," "plus," and "the total of. . ." are clues for addition.
"Difference" or anything that means distance or amount between two given values is a signal for subtraction.
When Linear dimensions are given and Area is to be found, it will be a multiplication equation. The words "times" and "by" usually mean multiply.
Fractions are often multiplied by some other number.
Ratios are usually division problems.
When a total amount is distributed among some number of people, or you need to find out how many people will get a given share or portion, it is a division equation.
Explanation:
It's much easier to explain with specific examples. Here is one.
We set up 15 rows of 6 seats in each row. How many seats are there altogether?
Of is the clue for multiplication Are becomes the equal sign.
15 × 6 = ? how many altogether?
90 = the number of seats.