2.NBT.B.7 — Add and Subtract Within 1,000

What 2.NBT.B.7 Covers

Students add and subtract three-digit numbers within 1,000, using concrete models, drawings, or place-value strategies rather than a memorized column algorithm. The key idea being introduced here: hundreds combine with hundreds, tens with tens, ones with ones — and sometimes a group of ten ones has to be "traded" for one ten, or a group of ten tens for one hundred (composing/decomposing). This standard is about understanding why the written method works, not just executing it quickly.

Where It Fits

Builds directly on 2.NBT.B.5 (the same place-value reasoning, one digit shorter). In Grade 3, 3.NBT.A.2 asks students to do the identical within-1,000 range from memory and with speed — this page is the "understand it" stage; that one is the "do it fast" stage.

Common Mistakes

• Regrouping tens into hundreds but forgetting to also regroup ones into tens in the same problem (e.g. 456 + 178).
• Writing a 0 in a place value that needs to "borrow across" it — e.g. 400 − 128, where the tens place is 0 and the borrow has to cascade from the hundreds.
• Losing track of which digits are hundreds vs. tens vs. ones once numbers reach three digits, especially when columns aren't visually aligned.

⚙️ 2.NBT.B.7 Practice Worksheet Generator

Numbers are locked to this standard's range (within 1,000) so every problem matches 2.NBT.B.7 exactly.

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