>>>>She is in 5th grade and this is her homework...
>>>>
>>>>So, what if it were 28.5 * 1.843? Then 28 * 1.8? 29 * 2? What are the rules? What is significant?
>>>
>>>For quick rounding, I would keep ONE significant digit in most cases.
>>>
>>>28.5 * 1.843 --> 30 * 2
>>>
>>>The idea is to keep the first digit in each number, and replace all other digits with zeroes - rounding the next digit up or down, as appropriate.
>>
>>Ok, a couple examples to make sure I understand:
>>
>>

>> 4.008 * 2.09 ------> 4 * 2
>>38.002 * 0.49 ------> 38 * .5
>>61.203 * 0.42 ------> 61 * .4
>> 0.98  * 7.61 ------> 1 * 8 (not sure about the 0.98 going to 1 on this one)
>>

>
>For quick estimates, just keep ONE significant digit. Convert all non-zero digits except the first to zero; if the digit dropped is 5 or more, increase the first digit by one (for rounding). The first example is correct, the second, I would change to 40 * 0.5 (notice the rounding); the third, to 60 * 0.4.
>
>The fourth example, once again, is correct: rounding to 1 s.d. means, in this case, rounding to the closest 0.1; 0.98 is closer to 1.0 than to 0.9. Or just look at the algorithm in the previos paragraph (the 8 is dropped, 0.9 is increased to 1.0).

Whew!

Ok, how did the 38.002 become 40 instead of 39? So, DIGIT is the key, not like whole number? But, isn't 40 comprised of two digits of 4 and 0?

How can this be at the 5th grade level?!