2. Addition and subtraction

Lesson

Do you remember how to round numbers?

The number $379$379 is plotted on the number line.

Round $379$379 to the nearest $100$100 and plot it on the blank number line

Let's see how we can estimate the answer to a subtraction problem, and an addition problem.

We want to estimate the answer to $258-26$258−26.

Round each of the two numbers to the nearest $10$10:

$258-26$258−26 is rounded to $\editable{}-\editable{}$− $=$=$\editable{}$ Find the value of $258-26$258−26.

Remember!

If we don't need an exact answer to a problem, we can use estimating to find out a close-enough answer. We can also use estimating to check our answers, so it is a great skill to learn!