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.
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
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
