Addition Shortcuts

Add by making tens. For $97 + 45$: think $(100 - 3) + 45 = 142$. For $68 + 57$: think $68 + 60 - 3 = 125$. Chain additions left to right: $234 + 567$ becomes $700 + 90 + 11 = 801$. Practice until you don't consciously think about the method. It should feel automatic.