Properties of addition and subtraction are easier to write with letters so one rule works for any numbers.
Commutative property of addition: a+b=b+a.
Associative property of addition: (a+b)+c=a+(b+c) — the sum does not depend on how you place parentheses.
Zero: a+0=0+a=a; subtracting zero: a−0=a.
Link between addition and subtraction: if a+b=c, then c−a=b and c−b=a; from a−x=b it follows that a=b+x. Check subtraction: add the subtrahend to the difference — you should get the minuend.
a+b=b+a — order of addends
(a+b)+c=a+(b+c) — parentheses in addition
a+0=a, a−0=a
From a+b=c follows c−a=b
Commutative property: the same sum
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