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## 2nd grade

### Course: 2nd grade > Unit 2

Lesson 4: Comparing 2 and 3 digit numbers# Comparing whole numbers

Sal compares 394 and 397.

## Want to join the conversation?

- Why do people compare numbers and how do they compare numbers?(5 votes)
- You can't really get far in this world without comparing numbers. For example, you need to compare numbers in the grocery store to figure out which item is cheaper. Or, you need to compare numbers to get statistics. Or, you need to compare numbers to see who's older. Comparing numbers is everywhere around us so it's really important to be able to know how. :)

You can use a number line to compare the numbers, but as you grow older and master the basic operation rules (subtraction & addition), you'll know which number is more or less than the other.(6 votes)

- Who created the greater than and less than symbols?(5 votes)
- Thomas Harriot did, in 1621.(8 votes)

- The crocodile will eat the bigger number or smaller number?(1 vote)
- The Crocodile's jaw or the opening of the symbol is towards the greater number closed part is towards the small number.(2 votes)

- Is infinity ever complete or is it just a value constantly moving? What about the number line?(1 vote)
- Infinity is infact a value that constantly keeps on growing.

Imagine numbers for example, the more zeros you add at the end of a number, the more it grows.

For example, 100, 1000, 100000, 100000000 and so on.

I hope that this helps your situation(2 votes)

- What if the question was like this: Is 300 greater than 250+100 what would we do?(2 votes)
- You should do 250+100 first. If you do it, you get 350. Then compare the numbers, 300<350. Now you know the answer.(1 vote)

- What would be greater in the case of "-5 ? -14" Is there a lesson on that by the way?(0 votes)
- -5 would be greater. Think of negatives as the opposite of positive/natural numbers. The larger a negative number, the less value it has.(2 votes)

- I am coaching my sister on this math, and is there a good mnemonic 7-year-olds can understand and relate to for place value?(0 votes)
- Well, as 7 year olds go, they have short attention spans. Like, if they see a fly, they'll stare at it. Oh look a shoe! Yep. It goes that fast. So you have to do something fun for them. Otherwise, they'll have their minds on other things. I tend to notice that 7 year olds like animals. Seeing as she's a girl, (I don't know what she likes as a person) maybe using unicorns to represent numbers would keep her attention span. Make up fun stories for her, using things that interest her. It may be childish, but unless she's the very rare 7-year-old-who-can-sit-still, it'll work.

Maybe a counting game? (Found this online when I was showing my younger brother this a few years back)

You need beans or other counters and small bags. The main rule is that you are ONLY allowed to use the words from one to ten when you count! In other words, you are NOT allowed to use words like eleven, thirteen, twenty, etc.

In the game, each player adds one more counting object to the common pile on the table, and says the amount of total objects in a broken-down form. For example, eleven is said as "ten and one", twelve is said as "ten and two", twenty is "two tens", twenty-five is "two tens and five", and so on.

Whenever a whole ten is fulfilled, those ten beans are bundled together into a bag.

You can modify the game so that on their turn, each player adds two beans to the pile instead of one. Another variation is to name the number both in the usual way and in the broken down form.

Next would come the representation of this idea on paper, with numbers. The crucial point in place value is that a certain position or place represents a certain size group. The digit in that place tells you how many of those certain size groups you have.(1 vote)

## Video transcript

Determine whether 394 is greater
than or less than 397. Then write the expression that
shows this using either this symbol or that symbol,
and this is actually the less than symbol. We'll think a little bit more
about how to remember that. That is the less than symbol
and this is the greater than symbol. So first of all, let's
just look at the two numbers: 394 and 397. So let me write them down. 394 and the other
number is 397. Now, they both have 3 hundreds,
so their hundreds place is equivalent. They both have 90 with that 9
there, but this is 300 plus 90 plus 4 and this is 300
plus 90 plus 7. And we know that 4
is less than 7. If you look on a number line,
4 comes before 7. If you're counting the 7, you're
going to pass up 4, so 394 is less than 397. And the way that we write that,
we would just write 394 is less than 397. And the way I remember that this
means less than is that the smaller number is on the
side that has kind of a smaller side. You can imagine this side
is much smaller than this side over here. We could also write
it the other way. We could write 397 is
greater than 394. And once again, the bigger
number is the side that this little thing is opening onto
or the side that has the bigger side of this
symbol right here. This point is the
smaller side. This out here is the
bigger side. That's where you put
the larger number. Greater than, less than.