486 + 387 = ?
Answer and explanation
873
486 + 387 = 873
Subjects
Arithmetic
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Sample exercises
327 − 168 = ?
Answer and explanation
159
327 − 168 = 159
19 × 10 = ?
Answer and explanation
190
19 × 10 = 190
Study notes
Addition within ten
Count both groups without counting any item twice.
Grades K–1Subtraction within ten
Start with the whole and take away the second number.
Grades K–1Addition within twenty
Make ten first when it helps.
Grades 1–2Subtraction within twenty
Check subtraction by adding the result back to the amount removed.
Grades 1–2Two-digit addition
Regroup ten ones as one ten when needed.
Grades 2–3Two-digit subtraction
Exchange one ten for ten ones when needed.
Grades 2–3Times tables to twelve
Multiplication represents equal groups.
Grades 2–4Division facts
Use the related multiplication fact; the divisor cannot be zero.
Grades 3–4Find the remainder
The remainder is at least zero and smaller than the positive divisor.
Grades 3–5Subtract signed integers
Subtracting a negative is adding its opposite.
Grades 6–8Balance two sides
Work out one side, then subtract the known part.
Grades 2–4Arithmetic · Formula sheet
Rules, conditions and small examples in one printable reference.
Grades K–2Arithmetic · Formula sheet
Rules, conditions and small examples in one printable reference.
Grades 3–5Arithmetic · Formula sheet
Rules, conditions and small examples in one printable reference.
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