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Lesson 5: Estimate to subtract multi-digit numbers

# Estimating when subtracting large numbers

Use estimation to find reasonable solutions to 2- and 3-digit subtraction problems.

## Want to join the conversation?

• I'm confused about how to estimate now. In the video, we are estimating by going up or down by 10s if the one-place value is greater or less than 5. - . So how come when estimating certain numbers that doesn't apply?

For example, during "Estimate to subtract multi-digit whole numbers" after the video numbers like

706 is estimated to be 700, not 710.
678 is estimated to be 700, not 680.
294 is estimated to be 300, not 290.
273 is estimated to be 300, not 270.

I thought when estimating you were only rounding the number up or down by 10 if the one place is lower or above 5 similar to how it was demonstrated in the video.

That could possibly be an error but if it's not can someone explain to me why certain numbers aren't rounded up or down by 10s but estimated by 100s and why some 10s digited numbers are rounded up when lower than 5 and vice versa? That would be good because that part wasn't talked about in the video.
• In this video, the numbers were rounded to the nearest 10, but in the examples you gave, all the numbers are rounded to the nearest 100.

So although 706 ends in 6, we still round down when rounding to the nearest hundred because 6 is closer to 0 than 100.

Whether you round to the nearest 10 or 100 will depend on how accurate you want your estimate to be. Rounding to the nearest 10 is more accurate, but rounding to the nearest 100 may be easier.
• Is it cumpulsory to use a curved equal sign?
• Yes. The curved equal sign ≈ means "approximately equal to". You are required to use this since the value you evaluated isn't the actual value, but instead simply an approximation.
• how do round manes numbers
• is life real
• yes it is real
• Pay attention to through
• I do not under stan
• how would we round by 5?