15 terms

commutative property of addition

numbers can switch places and the sum stays the same

associative property of addition

how numbers are grouped doesn't matter and the sum stays the same

identity property of addition

sum of any number and zero is that number

subtraction rule of zero a

number minus itself equals zero

subtraction rule of zero b

number minus zero equals itself

commutative example

8+5=5+8

associative example

(8+9)+3=8+(9+3)

identity example

81+0=81

subtraction rule a example

9-9=0

subtraction rule b example

8-0=8

about means

estimate

estimate

round the numbers then solve

round

solve then round the answer

check addition by

estimating

check subtraction by

adding