Mathematics · Grades 3–5
Number skills · Formula sheet
Rules, conditions and small examples in one printable reference.
Remember this
Round to the nearest ten
For positive whole numbers, inspect the ones digit.
0–4 → down; 5–9 → up
241 → 240
Greatest common factor
A factor divides a whole number without a remainder.
gcd(a,b) = gcd(b, a mod b)
gcd(123, 50) = 1
Least common multiple
Use positive whole numbers. A common multiple is divisible by both.
lcm(a,b) = |ab| / gcd(a,b)
9 × 19 ÷ 1 = 171
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Learning preview · teacher review required. Grade bands are approximate, not official curriculum alignment.