Welcome to the Big Number Lab!
In 4th grade, we are working with numbers in the thousands! Whether we are combining populations of two towns (Addition) or finding out how much farther one rocket flew than another (Subtraction), the rules of place value guide us.
The Secret of Regrouping
Sometimes, a column adds up to more than 9, or a number is too small to subtract from! That's when we regroup (also known as carrying or borrowing).
| Operation Strategy | How it Works (MathJax) |
|---|---|
| Carrying (Addition) | If the ones place adds to $13$, keep the $3$ and carry the $1$ to the tens place. $$ 458 + 225 = 683 $$ |
| Borrowing (Subtraction) | If you need to subtract $8$ from $5$, you must borrow $1$ ten from the neighbor! $$ 5,432 - 1,218 = 4,214 $$ |
| Place Value Alignment | Always stack your numbers vertically by place value: Ones over Ones, Tens over Tens. |
Solve the equation:
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+
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=
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Multi-Digit Master!
You successfully grouped and regrouped your way through the thousands place. Your lab experiments are complete!