2.NBT.B.5 — Add and Subtract Within 100

What 2.NBT.B.5 Covers

Students fluently add and subtract two-digit numbers within 100 using strategies grounded in place value — tens and ones, properties of operations, and the relationship between addition and subtraction — rather than the standard column algorithm alone. This is the first time regrouping (carrying and borrowing) shows up at scale.

Where It Fits

Relies on the single-digit fact fluency built in 2.OA.B.2 — every regrouping step is really a within-20 fact in disguise. The same place-value approach extends one digit further in 2.NBT.B.7 (within 1,000), and becomes a fluency expectation in Grade 3's 3.NBT.A.2.

Common Mistakes

• Forgetting to regroup — writing 47 + 38 as 7-tens-5-ones instead of carrying the extra ten.
• Subtracting the smaller digit from the larger one regardless of position, e.g. computing 52 − 28 as "5−2, 8−2" instead of borrowing correctly.
• Misaligning the ones and tens columns when the numbers have a different number of digits.

⚙️ 2.NBT.B.5 Practice Worksheet Generator

Numbers are locked to this standard's range (within 100) so every problem matches 2.NBT.B.5 exactly.

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