Finding the sum or total of two
numbers
Addition
Finding the difference between two
numbers
Subtraction
The answer to an addition problem
Sum
The answer to a subtraction problem
Difference
Estimation
Identity property
Commutative property
Rounding the addends, or
subtrahend and minuend to find an
approximate answer
Any number added to 0 stays the
same
The addends can be switched or
flipped and it doesn’t change the
sum
Opposite operations – addition is
the opposite of subtraction
Inverse
The total number of objects
Minuend
The number being subtracted or
taken out
Subtrahend
Related number facts
All the true number sentences that
can be created using the same three
numbers
Reorganizing numbers so they can
be subtracted or added
Regroup
Number sentence
Addend
A number sentence are the numbers
that are connected by operations and
their equivalent part
Addends are the two numbers that
are added together