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Lesson 7 of 9

The big picture

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4 min

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Every number has its own factor list.

Prime Time — the whole chapter on one screen
IdeaRememberExample
FactorsDivides exactly, nothing left over.12 → 1, 2, 3, 4, 6, 12.
MultiplesSteps you count up — never stops.6 → 6, 12, 18, 24…
PrimesExactly two factors: 1 and itself.7 → 1, 7.
CompositesMore than two factors.9 → 1, 3, 9.
DivisibilityA quick test, no dividing needed.348 → 2 and 3 fit.
Common factorsNumbers on two factor lists at once.12 & 18 → 1, 2, 3, 6.

Open Chapter 5, Prime Time, in your NCERT book. You have already met its main ideas here.