Number & Operations in Base Ten
Hundreds, Tens, and Ones
Understanding a three-digit number as hundreds, tens, and ones.
Bundling Tens into Hundreds
In Grade 1, a two-digit number was understood as a number of tens plus a number of ones. A three-digit number works the same way, with one more level added: ten bundles of ten combine into a single bundle of a hundred.
In a three-digit number, the leftmost digit shows how many hundreds, the middle digit shows how many tens, and the rightmost digit shows how many ones. The number 356 means 3 hundreds, 5 tens, and 6 ones — or 300 + 50 + 6.
Worked Example — Reading a Three-Digit Number by Place Value
Worked Example — Building a Number from Its Parts
Tip
Common Mistakes
Misreading a number's place values, such as thinking the middle digit of 472 represents hundreds instead of tens.
Always read place value from the left: the first digit of a three-digit number is hundreds, the second is tens, and the third is ones.
Forgetting a placeholder 0 when a number has no tens or no ones, such as writing 3 hundreds and 4 ones as '34' instead of '304.'
Every place must have a digit, even if it's 0. A number with 3 hundreds, 0 tens, and 4 ones is written 304, not 34.
Key Takeaways
- A three-digit number is made of hundreds, tens, and ones.
- Ten bundles of ten combine into one bundle of a hundred.
- A 0 must be written in any place with no value, so every digit keeps its correct position.
Summary
Understanding hundreds, tens, and ones extends the same place-value thinking from Grade 1 into three-digit numbers. The next lesson uses that same place-value understanding to compare which of two three-digit numbers is larger.
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