The number 222 has the digit 2 written three times. But those three 2s actually stand for completely different sizes. The first 2 means 200, the middle 2 means 20, and the last 2 just means 2. The very same digit can mean something totally different depending on which place it's in — that's place value.
This system, where each place is worth 10 times the one before it, is called base ten. Moving from right to left, the places go ones, tens, hundreds, thousands... each one 10 times bigger than the last. That's why any place with no value (an empty place) always needs a 0 written in it to hold that spot. Skip the 0, and every digit after it slides over one place and becomes a totally different number. Writing 20 as just "2" by dropping the empty place, for example, turns it into a completely different number than the one you meant.
The tool that makes this sense of place value visible is "place-value blocks." The ones place is a single small cube, the tens place is a rod made of 10 of those cubes stuck together, the hundreds place is a flat made of 10 rods stuck together, and the thousands place is a big cube made of 10 flats stacked up. Watching the block get exactly 10 times bigger with every place makes "place value grows by a factor of 10" feel like a real, visible difference in size — not just an abstract rule.
Reading big numbers out loud is closely tied to place value too. In English, we group digits in sets of three from the right, separated by commas, and give each group a new name: thousand, million, billion. That's why it helps to get in the habit of marking off groups of three digits from the right when reading a big number. For example, 12,345,678 splits into 12 | 345 | 678, and reads as "twelve million, three hundred forty-five thousand, six hundred seventy-eight."
Place value shows up all the time when counting money. Counting a mix of ten-dollar bills, one-dollar bills, and dimes is really just using place value. It's also the reason calculators and computers can work with huge numbers so quickly — they store and calculate numbers using this same place-value idea. Computers use base two (only 0s and 1s) instead of base ten, but the core idea — "each place is worth a fixed multiple more than the last" — is exactly the same.
A great way to practice with kids is to build big numbers using real objects — play money or place-value blocks. Ask questions like "how much is two ten-dollar bills, three one-dollar bills, and five dimes?", have them count out the objects to build the number, then practice reading that number back out place by place. Repeating this builds a solid sense of place value.
On our activity page, moving the slider for each place changes the number and size of the blocks in real time, and shows how the number is read aloud too. Move between 3-digit, 4-digit, and 5-digit (ten thousands) modes to build your sense of place value.