Factors and Multiples

When a number is said to be a factor of any other second number, then the first number must divide the second number entirely without leaving any remainder.
In simple words, if a number (dividend) is exactly divisible by any number (divisor), then the divisor is a factor of that dividend. 
For example:
12 is exactly divisible by 1, 2, 3, 4, 6, and 12, which means the remainder is 0. These numbers are called divisors or factors of 12
Facts about factors:

• 1 is a factor of every number.
• Every number is a factor of itself.
• Every factor of a number is an exact divisor of that number.
• Every factor is less than or equal to the given number.
• The number of factors of a given number is finite.

When the division of a dividend leaves no remainder, the dividend is said to be a multiple of the divisor.
For example:

Multiples of 7 are 7, 14, 21, 28,... They are greater than or equal to 7
Facts about multiples:

• Every multiple of a number is greater than or equal to that number.
• The number of multiples of a given number is infinite.
• Every number is a multiple of itself.