Basically there are 3 addition properties and they are associative property, identity property, and commutative property.
Commutative property is just changing the order of the addends. Example: 26+19+34+21= 21+34+19+26
Identity Property is just adding a 0 to the number that doesnt change anything. Example: 26+19+34+21 +0 = 100
Associative property is just changing the grouping of the addends. Example: (26+19) + (34+21)
I know these properties may be complicated i know inhate them too haha but i hope i helped :) if you want you can search up the distributive property too but its with multiplication and addition combined and its harder but i think these are the 3 main properties.
Hope this helps!