Add and subtract within 100: FAQ

Adding and subtracting within $100$100 is important because it builds a foundation for more complex math later on. Plus, it's helpful for everyday tasks like counting money or figuring out how many items you have.

Place value blocks can help us visualize the numbers we're working with. We can use the blocks to break down a number into tens and ones, and then use those parts to help us add or subtract.

One strategy is to break apart one of the numbers and make tens. For example, to add $58+7$58, plus, 7, we can break apart the $7$7 into $2$2 and $5$5. Then, we can add $58+2$58, plus, 2 to make $60$60, and add the remaining $5$5 to get a final answer of $65$65.

One strategy is to count backwards on a number line. For example, to subtract $5$5 from $42$42, we can start at $42$42 on the number line and count backwards five spaces to land on $37$37.

We should always read the problem carefully, and make sure we understand what it's asking us to do. We can underline or highlight important information, and draw pictures or use diagrams to help us visualize the problem. We can also write out equations to help us organize our work.