What is this skill?
Comparing three-digit numbers means deciding which of two numbers is greater, using the symbols > (greater than), < (less than) and = (equal to). Second graders compare numbers like 482 and 467 by looking at the places from left to right: first the hundreds, then the tens, and only if those match, the ones.
In 482 and 467, both have 4 hundreds, so the hundreds do not decide it. The tens do: 8 tens is more than 6 tens, so 482 > 467, no matter what the ones digits are. Children learn to stop at the first place where the digits differ, which is faster and more reliable than trying to picture both numbers whole.
Why it matters
Comparing numbers is a direct test of place value. A child who knows that the hundreds digit is worth far more than the tens and ones understands why 501 is bigger than 499, even though 499 has bigger digits. That understanding carries into ordering numbers, reading number lines, rounding and estimating.
It is also practical. Comparing prices, scores, distances and page counts all come down to this skill, and later the same left-to-right method is used for comparing numbers in the thousands, millions and decimals. The symbols themselves will appear in algebra, so getting comfortable reading them aloud now pays off for years.
Common mistakes
- Looking at the ones digit first, or at the biggest digit anywhere in the number, and deciding that 299 is greater than 310 because 9 is big. Point to the hundreds and ask "Which number has more hundreds?"
- Reading the symbols backward. A common tip is that the wide, open side faces the bigger number, and the point faces the smaller one. Reading the whole sentence out loud ("482 is greater than 467") also helps.
- Being thrown by the same hundreds digit. When both numbers start with 4, some children think they are equal. Practice pairs like 438 and 483 that have the same digits in different places.
- Forgetting that zero still counts as a place, as in comparing 405 and 450. Lining the numbers up one above the other makes the tens easy to compare.
How to help at home
- Play a card game: each player draws three cards (use 1 to 9, and let a face card be 0), arranges them into the biggest number they can, and the bigger number wins the round.
- Compare real numbers: prices at the store, house numbers on your street, or the page count of two books. Ask which is greater and how your child knows.
- Make the comparison symbols from two craft sticks and have your child place them between two numbers written on paper, then read the sentence aloud.
- Ask "What is a number between 467 and 482?" This builds the same skill from another direction and has many right answers.
Worked examples
These are real questions from the Tutorsaurus comparing three-digit numbers practice, with the answers worked out.
Example 1
789 ? 351
Choices: >, <, =
Answer: >. 789 > 351. Compare hundreds, then tens, then ones.
Example 2
840 ? 864
Choices: >, <, =
Answer: <. 840 < 864. Compare hundreds, then tens, then ones.
Example 3
759 ? 792
Choices: >, <, =
Answer: <. 759 < 792. Compare hundreds, then tens, then ones.