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# Estimating with multiplication

Sal estimates to find reasonable products to 1-digit by 2, 3, and 4-digit multiplication expressions.

## Want to join the conversation?

• Question: How do you know what number is a friendly number or not?

And how do you know when you are supposed to round a single-digit or ten-digit number up or down?

It looks like sometimes when estimating what to round up or down you sometimes have to round both numbers down like 16 to 15 and 1111 to 1000. I have trouble knowing what to round up or down if it's not asking for a friendly number.

This is a similar problem I had when estimating was first introduced in the 3rd-grade segments of Khan Academy. Those questions weren't fully mentioned besides rounding by 10s 100s, and 1000s.
• You round up if the number is five or higher you round down if lower than five
(1 vote)
• What does the squiggly equal sign mean.And why
• the squiggly equal sign means that the following phrase is approximately the right sum
for example 146+100 equals almost* 250

* I used "equals almost" insted of the squiggly equal sign, but thay mean the same thing

so the sum of this problem is
squiggly equal sign 250
(1 vote)
• what kind of sign is this ~
• I think this video is so helpful! Befor on this assignment i got only 25%, but when I watched this video I got 95%!💯
• That's great. So happy to see you learn :)
(1 vote)
• In the Estimate Products Lesson do you estimate the first or second number? I tried estimating the largest number but got it wrong when I tried!
• I am so confused with the video
• Well all you do is multiply to find the product. Then you find the awnser that is closer to the product. for example. 189*2 is 387. and the closes number to it is 400 if it were the smalles number in the awnsers. Hope this helped.
• why does estimates have to go with the digits that are gonna to multiply instead of the answer?
(1 vote)
• this is so great

now i know how to estimate
(1 vote)
• I do not get it how does that wherk.
(1 vote)
• wha- I got 8,670 for number 2😧