Class 3 (ICSE) • MathematicsChapter 2: Addition and Subtraction (3-digit)⭐ Topic 1
Addition and Subtraction (3-digit)
Addition and subtraction with 3-digit numbers use regrouping across hundreds, tens, and ones to find accurate totals and differences.
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When adding 3-digit numbers, we add ones first, then tens, then hundreds, regrouping (carrying) when a column totals 10 or more.
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Remember these!
- We add or subtract ones, then tens, then hundreds.
- We regroup (carry) when a column totals 10 or more.
- 456 + 278 = 734 using regrouping.
- Subtraction uses borrowing when needed.
- We borrow from the next column if a digit is too small.
- Practice builds confidence with larger numbers.
- This skill extends 2-digit regrouping.
- 3-digit maths needs careful step-by-step work.
Words to know
addition and subtraction (3-digit)