# Factors & Primes Worksheets > Prime factorization, GCD and LCM, prime or composite. Grades 4–6. Part of [Super Awesome Math](https://superawesomemath.com/index.md). Three kinds of practice with factors and multiples on a notebook grid. Write a number as a product of primes, smallest first, with one box per digit of each factor; find the greatest common divisor and the least common multiple of a pair; or mark each number prime or composite. The primes practice leans on the numbers that fool children, odd composites such as 51, 57 and 91 that pass the checks for 2 and 5. Numbers go up to 100 or 500, and the multiplication sign prints as × or ·, following the convention of each language. **Skills:** prime factorization, greatest common divisor, least common multiple, prime and composite numbers, divisibility. **Format:** printable, randomized on every load. **URL:** https://superawesomemath.com/worksheets/factors-and-primes **Grades 4–6** · Last updated: 2026-09-12 ## Settings - Practice: prime factors, GCD and LCM, or prime or composite - Range: numbers within 100 or within 500 - Sign: × or · - Columns: 2, 3 or 4, as many as the practice allows - Print an answer key ## Example problems - 84 = □ × □ × □ × □ - 90 = □ × □ × □ × □ - 51 → □ - 91 → □ ## Frequently asked questions **What is a prime factorization, and why write the factors in order?** Every whole number above 1 is a product of primes in exactly one way, apart from the order: 84 is 2 × 2 × 3 × 7. Writing the factors smallest first gives every problem a single answer to check against, and it makes repeated factors easy to count, which is what the GCD and LCM are built from. **How do you find the GCD and LCM of two numbers?** Factorize both. The greatest common divisor multiplies the primes they share, as many times as both have them; the least common multiple multiplies every prime either one has, as many times as the one with more. For 12 = 2 × 2 × 3 and 18 = 2 × 3 × 3 that gives a GCD of 6 and an LCM of 36. **Why does the sheet keep showing numbers like 51 and 91?** Those are the composites that look prime. A child who checks for 2 and 5 and stops will call 51 prime, but it is 3 × 17, and 91 is 7 × 13. About half of every primes page is composite, and most of those are odd numbers not ending in 5, so the only way through is to keep dividing. **Which range should I start with?** Within 100 suits grades 4 and 5, where the primes to try are 2, 3, 5 and 7. Within 500 needs 11, 13, 17 and 19 as well, and a factorization there can end with a two- or three-digit prime, so it fits grade 6 or a child who already factorizes quickly. ## How to use 1. Open https://superawesomemath.com/worksheets/factors-and-primes. 2. Adjust the settings; they are saved in the browser. 3. Press Regenerate for a new random set, then Print. ## Other Super Awesome Math worksheets - [Add & Subtract](https://superawesomemath.com/worksheets/add-subtract.md): Addition & subtraction drills - [Column Addition & Subtraction](https://superawesomemath.com/worksheets/column-addition.md): Vertical multi-digit addition and subtraction - [Multiplication](https://superawesomemath.com/worksheets/multiplication.md): Times tables & grid practice - [Column Multiplication](https://superawesomemath.com/worksheets/column-multiplication.md): Long multiplication practice - [Division](https://superawesomemath.com/worksheets/division.md): Division facts, with or without remainders - [Long Division](https://superawesomemath.com/worksheets/long-division.md): Long division practice - [Comparison](https://superawesomemath.com/worksheets/comparison.md): Greater than, less than, equal - [Rounding](https://superawesomemath.com/worksheets/rounding.md): Round to nearest 10, 100, 1000 - [Fractions](https://superawesomemath.com/worksheets/fractions.md): Simplify, find equivalent fractions and compare - [Add & Subtract Fractions](https://superawesomemath.com/worksheets/add-subtract-fractions.md): Like and unlike denominators, and mixed numbers - [Decimals](https://superawesomemath.com/worksheets/decimals.md): Column addition and subtraction, and × ÷ by 10, 100, 1000 - [Order of Operations](https://superawesomemath.com/worksheets/order-of-operations.md): Which operation comes first - [Equation Explorer](https://superawesomemath.com/worksheets/equation-explorer.md): Solve equations interactively - [Solve for x](https://superawesomemath.com/worksheets/solve-for-x.md): One-step, two-step and x-on-both-sides equations - [Patterns](https://superawesomemath.com/worksheets/patterns.md): Number sequences & series - [Bongard Problems](https://superawesomemath.com/worksheets/bongard-problems.md): Find what the left boxes share and the right ones lack ## For developers and AI agents Every page is also available as Markdown: append `.md` to the path or request it with `Accept: text/markdown`. - [llms.txt](https://superawesomemath.com/llms.txt): index for language models - [worksheets.json](https://superawesomemath.com/worksheets.json): machine-readable worksheet catalog - [Sitemap](https://superawesomemath.com/sitemap.xml)