Number system problems involve finding unknown numbers using given conditions. Key concepts: consecutive numbers, natural numbers, factors, multiples, odd/even numbers.
Key Formulas
Consecutive Numbers
Let numbers be n, n+1, n+2...
For even: n, n+2, n+4...
Sum of n natural numbers
n(n+1)/2
Quick formula.
Sum of squares
n(n+1)(2n+1)/6
Used in advanced problems.
⚡ Shortcut Tricks
#1
For two consecutive numbers: n and n+1. Their product = n²+n.