Number Theory
Primes, factors, GCD, LCM, and divisibility rules - the building blocks of number sense.
To find GCD(a,b): repeatedly replace the larger with the remainder until 0. Then LCM = a×-b ÷ GCD.
Visual Methods
Level Visual Guides
30 levels. Each level opens as 6 visual blocks.
Level 1 - foundation
Primes (≤ 30)
6 image blocks
Level 2 - foundation
Primes (≤ 50)
6 image blocks
Level 3 - realistic untimed
Primes (50-200)
6 image blocks
Level 4 - foundation
Primes (100-500)
6 image blocks
Level 5 - foundation
Divisibility intro (2, 3, 5)
6 image blocks
Level 6 - foundation
Divisibility (2-6)
6 image blocks
Level 7 - foundation
Divisibility (3-9)
6 image blocks
Level 8 - realistic untimed
Divisibility (all small rules)
6 image blocks
Level 9 - foundation
GCD (small, ≤ 30)
6 image blocks
Level 10 - foundation
GCD (≤ 50)
6 image blocks
Level 11 - build-up
GCD (≤ 80)
6 image blocks
Level 12 - build-up
GCD (≤ 120)
6 image blocks
Level 13 - realistic untimed
GCD (≤ 200)
6 image blocks
Level 14 - build-up
GCD (≤ 300)
6 image blocks
Level 15 - build-up
GCD mastery (≤ 500)
6 image blocks
Level 16 - build-up
LCM (≤ 12)
6 image blocks
Level 17 - build-up
LCM (≤ 18)
6 image blocks
Level 18 - realistic untimed
LCM (≤ 25)
6 image blocks
Level 19 - build-up
LCM (≤ 35)
6 image blocks
Level 20 - build-up
LCM (≤ 50)
6 image blocks
Level 21 - mastery
LCM (≤ 60)
6 image blocks
Level 22 - mastery
LCM mastery (≤ 80)
6 image blocks
Level 23 - realistic untimed
Rules - small (2, 3, 4, 5)
6 image blocks
Level 24 - mastery
Rules - even (4, 6, 8)
6 image blocks
Level 25 - mastery
Rules - digit-sum (3, 9)
6 image blocks
Level 26 - mastery
Rule for 7
6 image blocks
Level 27 - mastery
Rule for 11
6 image blocks
Level 28 - realistic untimed
Rule for 12
6 image blocks
Level 29 - mastery
Rules - all (small N)
6 image blocks
Level 30 - mastery
Rules mastery (4-digit N)
6 image blocks
Practice this category
Use the same method on live number theory levels.
Start Number Theory Workout