But her example shows that it rounds to .8 and the answer is 3.2, not 4. This is the example that she is supposed to follow. It sounds like Hilmar is on the right track with the first digit logic and all that, but not you have me feeling unsure again.

>For 5th grade math (learning to approximate):
>
>.843 rounds to 1
>4.2 rounds to 4
>4 x 1 =4
>
>
>
>>This is a sample problem out of a math workbook. I get that "estimating" essentially means performing calculations on rounded values, but they are mixing the places they round to in the example below. Why isn't it either 1 x 4 or 0.8 x 4.2? Not quite getting how they are doing that. I thought with rounding, you had to know the place you wanted to round to in order to have the product be valid.
>>
>>

>>Estimate Decimal Products
>>-------------------------
>>
>>Estimate 4.2 x 0.843
>>
>>  0.843 -------->   0.8
>>x   4.2 -------->  x  4
>>                   ====
>>              about 3.2
>>
>>Both factors are rounded
>>down. The actual product
>>is greater than 3.2.
>>