Multi-Digit Addition & Subtraction
📋 What it is
Line up place values, then add or subtract column by column, carrying or borrowing as needed.
🗣️ Coach says
Big-number adding is just careful lining-up. Match ones with ones, tens with tens. When a column overflows past 9, carry the extra to the next place; when you can't subtract, borrow from the left.
🧠 Memory hook
Line up the places. Carry when a column tops 9; borrow when the top digit is too small.
😂 Giggle
Why did the number 1 feel lonely?
Because it was odd — and the only one!
😲 Whoa!
The "carrying" method you use is over 1,000 years old and spread across the world from Indian and Arabic mathematicians.
✅ Quick check: When adding 47 + 38, why do you "carry the 1"?
Say your answer out loud first — then reveal.
7 + 8 = 15, which is more than one digit; the 1 (ten) carries to the tens column.
A column can only hold 0–9, so the overflow moves to the next place value.
🧪 Try it! (2 minutes)
Add two 3-digit numbers on paper, lining up the columns. Watch where a carry happens.