Alex is mailing an envelope that weighs 0.346 pounds. what is the weight of the envelope rounded to the nearest hundredth

The hundredth place is the second number on the right side of the decimal place. In this case, it is the 4 in the number you listed above. 

Rounding is simple, once you get the hang of it. :)

To round on the right side of the decimal, you look at the number to the right of the number. If the number to the right of that number is five or over, the number rounds up. But, if it is less than five, the number remains the same. Either way, the number/s to the right of the one you are rounding disappear after you are done.

So let's look at your equation. The number you wish to round up- the hundredths place is the number 4. The  number to the right of the four is a six. Since that is five or over, we round up. So the number would end up being .35 pounds to the nearest hundredth. 

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