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9×GooGooCalc⌕

Greatest Common Factor (GCF)

The ladder method — divide both numbers together until nothing is left in common.

First number · Second number

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Grades 5–6

Prime Factorization

A factor tree that grows branch by branch, with the reason each prime was chosen.

Grades 5–6

Least Common Multiple (LCM)

Same ladder as the GCF, but you multiply in an L shape — down the side and along the bottom.

Grades 4–6

Divisibility Rules

Test one number against every rule at once, and see why each one works.

Grades 4–5

Factor Pairs

Every pair that multiplies to your number — and why you only test up to the square root.