Prime Numbers and Whole Numbers

Factor

A factor is a number which divides another number exactly.

Examples:

To find the factors of 24, 72, 100:

• 24 = 2 × 2 × 2 × 3
• 72 = 2 × 2 × 2 × 3 × 3
• 100 = 2 × 2 × 5 × 5

The numbers 2, 3, 5 are called factors.

Prime Factor

A prime factor is a prime number which divides a given number exactly.

Example:

57 = 3 × 19

The numbers 3 and 19 are prime factors.

Electrical Quantities

Force

In C.G.S System:
Force (Dyne) = Mass (g) × Acceleration (cm/s²)

In F.P.S System:
Force (Poundal) = Mass (lb) × Acceleration (ft/s²)

In M.K.S System:
Force (Newton) = Mass (kg) × Acceleration (m/s²)

Lowest Common Multiple (L.C.M)

Definition

The Lowest Common Multiple (LCM) of a group of numbers is the smallest number that is exactly divisible by all the given numbers.

Prime Factorization Method

Example 1: Find LCM of 20, 66, 128

• 20 = 2 × 2 × 5
• 66 = 2 × 3 × 11
• 128 = 2 × 2 × 2 × 2 × 2 × 2 × 2

Take highest powers of all prime factors:

LCM = 2⁷ × 3 × 5 × 11 = 42240

Example 2: Find HCF of 78, 128, 196

Temperature

Pressure

Circular Unit

Radian

Relationship between Radian and Degree

• 1 Radian = 180° / π
• 180° = π Radian
• 1 Degree = π / 180 Radian

Power

Work

Units of Volume and Capacity