For the first one: a cent is in the hundredths place, so want you want to do is round the number to two decimal places. When you are rounding, if the number is equal to or greater than 5 you add 1 to the previous number, if it is less than 5 the number before stays the same. For example:
$10.006 rounded to the nearest cent. We want to end up with two decimal places so we'll take the third one and round. 6 is greater than 5 so we add 1 to the 0 and get: $10.01
The reason we do this, is because w're trying to round to the nearest ten. If the number is 5 or greater, we round up, because 5 and up are closer to 10. If it is less than 5, we round down to the nearest 10, because 4 and under are further from ten. That doesn't really make sense though so I'll give another example:
16 rounded to the nearest ten is 20.
13 rounded to the nearest ten is 10.
26 rounded to the nearest ten is 30.
And so on. Even if there is a decimal there, the system doesn't change.
2.9 rounded equals 3.0
16.7 rounded equals 17.0
15.3 rounded equals 15.0
That will probably help with the first two problems.
The sales tax ones are easier, once you know how to do them. You'll have to forgive me if I don't explain this right. I don't really like calculating tax. But who does?
So-and-so buys a $3.99 toy and a $1.49 candy bar. If the sales tax is 6.7%, what is the final price?
First you add the individual prices up.
$3.99+$1.49= $5.48
Next you calculate the tax. To calculate tax you multiply the total price by the tax (in decimal form).
$5.48*0.067=0.36716
(We round that number to the nearest cent, (take the third decimal place and round into the second) 7 is closer to 10, so we round up.)
$5.48*0.067=$0.37
Now add that number to the original price to get the final price.
$0.37+$5.48= $5.85
The final price of the candy bar, the toy, and the tax is $5.85.
I could give you another example, if you'd like. But I think you'll probably be able to figure it out from there. ^_^ I hope that helps!
(Could someone check my work, please? )
