Even number: number divisible by 2

Prime number: is a natural number greater than 1 that has only two factors (1 and the number itself).

2 is an even number because it can divide itself to obtain 1 and it is also a prime number because no other number can divide it except 1 and itself.

Integers

These are the set of all whole numbers but it includes a negative set of natural numbers also. Hence whole numbers and natural numbers are subsets of set of integers. "Z" represents integers and the set of integers include, Z = {...,-5,-4,-3,-2,-1,0,1,2,3,4,5,6,7,8,...}

Prime number is a number that is divisible only by itself and 1 (e.g. 2, 3, 5, 7, 11)

To express a number as a product of prime factors express the number as a multiple of prime numbers and simplify in a form of indexes

108 = 2 x 54

108 = 2 x 2 x 27

108 = 2 x 2 x 3 x 9

108 = 2 x 2 x 3 x 3 x 3

Now apply the law of indexes

a^m x aⁿ = a^{m + n}

Thus if the bases are the same and are multiplying, you can add the powers

a = a¹

Thus every number is raised to the power 1

108 = 2 x 2 x 3 x 3 x 3 = 2¹ x 2¹ x 3¹ x 3¹ x 3¹

108 = 2¹⁺¹ x 3¹⁺¹⁺¹

108 = 2² x 3³

The significant digits of a number are the digits that have meaning or contribute to the value of the number. Sometimes they are also called significant figures.

Which digits are significant?

There are some basic rules that tell you which digits in a number are significant:
• All non-zero digits are significant
• Any zeros between significant digits are also significant
• Trailing zeros to the right of a decimal point are significant

7352.4658 has 8 significant figures (7,3,5,2,4,6,5 and 8). Count from the left, three times to land on the three significant figure. If the next digit is 5 or more, you add 1 to the digit the count ends if not you keep that digit and replace the remaining digits by zeros till the decimal point.

⇒ 7352.4658 = 7350 three significant figures

41 has only two factors (1 and itself) hence a prime number and not a composite number.

In order words, no other number can divide 41 without a remainder except 1 and 41.

Factors of 24 = {1, 2, 3, 4, 6, 8, 12, 24}

Factors of 39 = {1, 3, 13, 39}

Factors of 65 = {1, 5, 13, 65}