TOPIC 1 · GRADES 3–4
Addition and Regrouping
Add by place value and trade 10 ones for 1 ten.
BIG IDEA
Line up equal place values. When a column makes 10 or more, regroup 10 of that unit as 1 of the next larger unit.
WHAT TO KNOW
- Write ones below ones, tens below tens, and hundreds below hundreds.
- Add from the ones place so a regrouped ten is ready for the tens column.
- Estimate first and use subtraction to check an addition answer.
WATCH OUT
The small carried 1 means one ten or one hundred—not one single unit.
TRY IT
Change the addends and watch ten ones bundle into a new ten.