Number System - Part 1 of 5

Number System (Part 1 of 5)

Important Formulas

This includes all the important formulas of this chapter which will ultimately helps you to solve the questions of Number System rapidly and correctly !!

1. (a + b)(a - b) = (a² - b²)
2. (a + b)² = (a² + b² + 2ab)
3. (a - b)² = (a² + b² - 2ab)
4. (a + b + c)² = a² + b² + c² + 2(ab + bc + ca)
5. (a³ + b³) = (a + b)(a² - ab + b²)
6. (a³ - b³) = (a - b)(a² + ab + b²)
7. (a³ + b³ + c³ - 3abc) = (a + b + c)(a² + b² + c² - ab - bc - ac)
8. When a + b + c = 0, then a³ + b³ + c³ = 3abc.
9. (a+b)²−(a−b)²=4ab
10. (a+b)²+(a−b)²=2(a²+b²)
11. (1 + 2 + 3 + .....+ n) = n (n + 1 ) / 2
12. (1² + 2² + 3² + ..... + n²) = n ( n + 1 ) (2n + 1) / 6
13. (1³ + 2³ + 3³ + ..... + n³) = n² (n + 1)² / 4
14. Dividend = (Divisor x Quotient) + Remainder