Build fluency with adding and subtracting
These are inverse operations - they "undo" each other.
Order doesn't matter:
Grouping doesn't matter:
Adding zero doesn't change the number:
Line up by place value and add column by column:
& 347 \\ + & 285 \\ \hline & 632 \end{array}$$ **Remember:** Carry when a column sum is 10 or more. ## Subtraction Subtraction finds the **difference** between numbers. $$15 - 8 = 7$$ This means: 15 is 7 more than 8. ## Subtracting Multi-Digit Numbers $$\begin{array}{r} & 534 \\ - & 267 \\ \hline & 267 \end{array}$$ **Remember:** Borrow (regroup) when the top digit is smaller. ## Mental Math Strategies ### Make a Ten $8 + 5 = 8 + 2 + 3 = 10 + 3 = 13$ ### Count Up for Subtraction $63 - 47$: From 47 to 50 is 3, from 50 to 63 is 13. Total: 16 ### Break Apart Numbers $47 + 36 = 47 + 30 + 6 = 77 + 6 = 83$