Worked examples
Two examples
Example 1
(3 × 104)(2 × 105) =
- Multiply the first numbers: 3 × 2 = 6.
- Add the exponents: 4 + 5 = 9.
Answer: 6 × 109
Example 2
(5 × 103)(4 × 102) =
- 5 × 4 = 20, and 3 + 2 = 5: 20 × 105.
- 20 is 10 or more: 2 × 101, so add 1 to the exponent.
Answer: 2 × 106
Where this is taught: Quiz 32: Scientific Notation, “Multiplying and dividing: Quiz 31’s rules do the work”
The drill
Ten problems
This drill also has challenge problems. They use the same skill, set up the way the GED test sometimes sets up a problem, so that it looks new at first.
How many:
Type each answer like 4.5 x 10^6 (an x or a * is fine, and so is 4.5e6). The first number must be at least 1 and less than 10. Then press Check my answers at the bottom.Write each answer in scientific notation on the line. The answer key, with the reasoning, is on the last page.