The following are
some key words found in word problems, which may help students determine the
operation (s) needed to solve their word problems.
Addition

increased by,
more than, combined, together, total, sum, added to 
Subtraction

decreased by,
minus, less, difference between, less than, fewer than 
Multiplication

of, times, cubed, multiplied by, product of, twice, doubled,
triple,
increased/decreased by a factor of (this type can involve both addition or subtraction and multiplication!) 
Division

per, out of, groups, sections, ratio, unit rate, quotient,
percent (divide by 100) 
Equals

is, are, was, were, will be, gives, yields
