Zachary got $200 for his birthday. He bought a $50 stereo, 4 CDs at $9.99 each, and a 6-pack of root beer for $5.60. He put the rest in the bank. (Man, good taste in soda and he's saving for his future? Get him while he's single, ladies.) How much did Zachary put in the bank?
Answer
$200 - $50 - (4 x $9.99) - $5.60 = $104.44
To figure out the
total cost of 4 CDs at $9.99 each, we don't actually have to multiply
$9.99 by 4. That's too much work. Instead, we can round and then adjust
our figure later on to be more exact. Trust us—this will save you
valuable CD-buying time in the long run.
$9.99 is almost exactly
$10, so the CDs cost about $40 total. However, this estimate is $0.01
(one cent) too high for each CD. Since there are 4 CDs, the estimate is 4
cents too high. Instead of $40, the CDs cost $39.96. Well, golly gee,
that sounds a whole lot cheaper than $40! What marketing genius came up
with that idea? He should get a raise!
