In the last lesson, you learned how to estimate sums.
The steps are the same for estimating differences.
You can estimate a difference by rounding each number first.
Then you subtract the rounded numbers to find an answer that's close to the true difference.
Let's estimate a few differences together.
836 - 249 ≈ ?
If we want to know the difference quickly, we don't have to find the exact answer now.
We can estimate the difference instead.
The first thing to do is round each number.
What's 836 rounded to the nearest hundred?
Correct, 800.
What's 249 rounded to the nearest hundred?
You got it. It's 200.
Now, subtract the rounded values.
So, the difference of 836 - 246 is about 600.
836 - 249 ≈ 600
Tip: We don't use the equal sign when estimating differences. Instead we use this approximate symbol that is made up two squiggly lines (≈). It means "almost equal to", or "approximately equal to".
Estimate 8,803 - 1,146.
What's 8,803 rounded to the highest place value, the thousands place?
Correct, 9,000.
What's 1,146 rounded to the nearest thousand?
Very good, 1,000.
We now subtract the rounded numbers.
8,803 - 1,146 ≈ 8,000
Great job estimating differences.
Now, complete the practice.