Rounding is a way to make numbers simpler and easier to work with. We use rounding every day when we estimate prices at the store, measure distances, or count large groups of objects. Let's see how it works with a number line. Here we have the number 23. We can see it's closer to 25 than to 20, so 23 rounds to 25. This makes our number friendlier and easier to remember!
Now let's learn the fundamental rounding rule that works for any number. First, look at the digit to the right of the place you're rounding to. If that digit is 5 or greater, you round up. If it's less than 5, you round down. Let's see this with an example. To round 47 to the nearest ten, we look at the ones place, which is 7. Since 7 is greater than 5, we round up from 40 to 50. This simple rule will help you round any number correctly!
Now let's focus on rounding to the nearest ten. Remember our rule: look at the ones digit. If the ones digit is 5 or greater, round up to the next ten. If it's less than 5, round down. Let's see this on our number line. For 23, the ones digit is 3, which is less than 5, so we round down to 20. For 27, the ones digit is 7, which is greater than 5, so we round up to 30. The number line helps us see which ten each number is closest to!
Now let's extend our rounding skills to hundreds. The same rule applies, but now we look at the tens digit instead of the ones digit. To round to the nearest hundred, look at the tens place. If the tens digit is 5 or greater, round up to the next hundred. If it's less than 5, round down. Let's see our examples: 234 has a tens digit of 3, which is less than 5, so we round down to 200. For 267, the tens digit is 6, which is greater than 5, so we round up to 300. The pattern is the same, just with bigger numbers!
Now let's practice with a complete problem that combines both types of rounding. We'll round 347 to both the nearest ten and the nearest hundred. First, to round to the nearest ten, we look at the ones digit, which is 7. Since 7 is greater than or equal to 5, we round up to 350. Next, to round the original number 347 to the nearest hundred, we look at the tens digit, which is 4. Since 4 is less than 5, we round down to 300. So 347 rounds to 350 when rounding to tens, and to 300 when rounding to hundreds. Practice makes perfect!