Estimated Answer: 30
Work: Since 2.31 is below 2.50, I rounded is back down to 2. Since 2.58 is above 2.50, I rounded it up to 3, and Since 5 isn't a decimal, it stays at 5. So, the new "Estimated" multiplication problem is 2 x 3 x 5 = 30
Check: So, lets do the original equation. The answer is 29.799, which is very close, so (Check) I hope this helps, and Happy Holidays! :)