Mental addition
School taught you to add from the right, carrying as you go — perfect for paper, painful in your head. Mental addition works from the big end instead: hundreds first, then tens, then ones.
These three methods (left-to-right, compensation, making tens) turn almost any addition into two or three small, forgettable-proof steps.
Method 1 · Level 1
Left-to-Right Addition: Big Numbers First
Add from the left: big parts first, small parts last. 476 + 267 = 600 + 130 + 13 = 743.
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Method 2 · Level 2Addition Compensation: Round, Add, Then Correct
297 + 468: round 297 to 300, add (768), then subtract the 3 you borrowed: 765.
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Method 3 · Level 1Making Tens: Reorder to Build Friendly Numbers
Reorder the sum so friendly pairs combine first: 47 + 38 + 13 → 47 + 13 = 60, then 60 + 38 = 98.
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