I'm not sure about problem #24, I attempted to work it out.
a.)2800-2.8*10^3
b.)86.30*10^2
c.)0.0076-7.6*10^-3
d.)15.0*10^8
?if this is correct, does it then want me to list in order of size?
The question asks for order-of-magnitude estimates. I posted this to today's page as an answer to another student's question. However I didn't link that page until just now, so you wouldn't have had a chance to look at it, and I'm posting this answer to your site:
To do an order-of-magnitude estimate you first put the number into scientific notation, then round off the first number to the nearest 10.
When rounding to the nearest 10:
Numbers from 1 to 5 round off to 1.
Numbers from 5 to 10 round off to 10.
The order-of-magnitude estimate is obtained by expressing the number in scientific notation, and rounding the first factor to the nearest 10.
So, for example, rounding to the nearest 10:
3.5 rounds off to 1
8.2 rounds off to 10
4.789 rounds off to 1
6.025 rounds off to 10
We use this idea to round off each of the following:
75,000 = 7.5 * 10^4. Rounding the first factor 7.5 to the nearest 10 we get 10, so our order-of-magnitude estimate becomes 10 * 10^4, which is 10^5.
1259 = 1.259 * 10^3. Rounding the first factor 1.259 to the nearest 10 we get 1, so our order-of-magnitude estimate becomes 10 * 10^3, which is 10^4.
.0093 = 9.3 * 10^-4. Rounding the first factor 9.3 to the nearest 10 we get 10, so our order-of-magnitude estimate becomes 10 * 10^-4, which is 10^-3.