Ordering three-digit numbers follows a hierarchy: compare hundreds first, then tens, then ones. Numbers can be arranged from least to greatest or greatest to least using place-value understanding.
When you learned to compare two-digit numbers, you discovered a key rule: look at the tens place first. If the tens digits differ, the number with the bigger tens digit is larger — no matter what the ones digit says. You can extend exactly the same logic to three-digit numbers, adding one step at the front: start with the hundreds place.
Think of a three-digit number as having three slots, each with a different level of importance. The hundreds place is the most important — it tells you roughly how big the number is. The tens place is the middle slot, used only when the hundreds digits are equal. The ones place is the tiebreaker, used only when both hundreds and tens match. This three-step process is called comparing by place value, and it is the same strategy you used with two-digit numbers, just with one extra layer added at the front.
Here is a concrete example: compare 453 and 481. Both have a 4 in the hundreds place, so hundreds are tied — move to tens. 453 has 5 tens and 481 has 8 tens. Since 5 < 8, we conclude 453 < 481. We never needed to look at the ones place. Now try 327 vs. 319. Hundreds are tied (both 3). Tens: 327 has 2 tens, 319 has 1 ten. Since 2 > 1, we conclude 327 > 319 — the ones digits are irrelevant.
Ordering a list of numbers from least to greatest (or greatest to least) is just comparing done repeatedly. A helpful strategy is to sort by hundreds first — group all the 100s together, all the 200s together, and so on. Within each hundreds group, sort by tens, then by ones. This is like sorting a stack of envelopes: rough groupings first, then fine-tuning within each group. With practice, this left-to-right place-value scan becomes automatic and fast.