Magnitude Estimates 

100,000s

10,000s

1,000s

100s

10s

1s

 

  •  Magnitude Estimate is a very rough estimate that answers the question:

Is the solution in 1s? 10s? 1,000s ? 10,000s? 

  • How to make a magnitude estimate:

1. Round the numbers to the nearest 1, or 10, or 100, etc.

2. Make the calculation.

3. Determine if the solution is in 1s, 10s, 100, 1,000s, etc. 

  • For example:

Make a magnitude estimate for 356 * 17: 

1. Round the 356 to the nearest 100:  400.

2. Round the 17 to the nearest 10:  20.

3. Multiply the estimates:  400 * 20 = 8,000

4. The solution of 356 * 17 is in the 1,000s.

5. To check, the actual solution is: 6,052 

  • Another example:

Make a magnitude estimate for 24.8 * .7: 

1. Round the 24.8 to the nearest 10: 25

2. Round the .7 to the nearest 1: 1

3. Multiply the estimates: 25 * 1 = 25

4. The solution of 24.8 * .7 is in the 10s.

5. To check, the actual solution is: 17.36