Three-Digit Addition Practice
20 questions · 60 seconds · numbers 100–999, vertical format
Free · no login · instant feedback on every answer
Scale the algorithm up: three-digit addition in vertical format with numbers from 100 to 999. Sums regularly cross into the thousands, and carries can ripple through two columns — ones into tens, tens into hundreds — which is exactly the skill that separates knowing the method from owning it.
Three-digit addition is where the column habit becomes permanent. A student who works right to left, carries cleanly twice in a row, and trusts the process on 587 + 649 has internalized place value well enough that four digits, five digits, or decimals later on change nothing.
Tips That Make It Stick
- Right to left, every time. Ones, then tens, then hundreds. Working left to right feels natural to readers — and breaks the moment a carry appears.
- Expect chained carries. In 587 + 649, the ones carry into the tens AND the tens carry into the hundreds. Saying each carry out loud keeps the chain honest.
- Estimate first. 587 + 649 is roughly 600 + 650 = 1,250. A five-second estimate flags a dropped carry instantly, because the wrong answer lands hundreds away.
Frequently Asked Questions
What grade practices three-digit addition?
Three-digit addition with regrouping is a 2nd and 3rd grade skill — introduced late in 2nd grade and expected to be fluent by the end of 3rd grade.
Why does my child add the hundreds first?
Reading habits — we read numbers left to right, so children naturally start there. The algorithm needs right to left so carries flow upward. Estimating first satisfies the urge to look at the big digits, then the algorithm handles the exact answer.
Is this three-digit addition game free?
Yes — completely free, no login or download. Matching printable three-digit worksheets with answer keys are free too.
📝 Matching Printable Worksheets
Prefer paper practice? These free PDF worksheets cover the same skill — each includes an answer key: