Adding Or Subtracting Numbers In Scientific Notation

In this lesson, we will look at some examples of adding and subtracting numbers in scientific notation (Scientific notation is called standard form in the UK)

Related Topics: More Scientific Notation Lessons

Scientific Notation: Addition and Subtraction

To add or subtract two numbers in scientific notation:

Step 1: Adjust the powers of 10 in the 2 numbers so that they have the same index. (Tip: It is easier to adjust the smaller index to equal the larger index).

Step 2 : Add or subtract the numbers.

Step 3 : Give the answer in scientific notation.

Example :

Evaluate 2 × 10³ + 3.6 × 10⁴, giving your answer in scientific notation.

Solution:

Text Box: 2 × 103 + 3.6 × 104 = 0.2 × 104 + 3.6 × 104 (change to the same indices) = (0.2 + 3.6) × 104 (add the numbers) = 3.8 × 104 (answer in scientific notation)

Example :

Evaluate 7 × 10⁵ – 5.2 × 10⁴, giving your answer in scientific notation.

Solution:

Text Box: 7 × 105 – 5.2 × 104 = 70 × 104 – 5.2 × 104 (change to the same indices) = (70 – 5.2) × 104 (subtract the numbers) = 64.8 × 104 = 6.48 × 105 (answer in scientific notation)

Video

This video explains how to add and subtract numbers written in scientific notation, whether or not they have the same exponent.

This video explains.why when adding and subtracting numbers in scientific notation, you have to make sure the exponents are the same.

This video reviews scientific notation and shows how to add and subtract in Scientific Notation.