It's simple math.

If you have three children under 10 and you multiply that times three pairs of jeans plus $30 because they're buy one, get one for $10, subtract 9.25 percent from the total and divide that by a faltering economy, what is the sum of your purchases?

Answer: A host of happy parents flooding stores this weekend to cash in on Tennessee's fifth annual sales tax holiday.

The holiday begins at 12:01 a.m. Friday and ends at 11:59 p.m. Sunday.

Tennessee residents can use those 72 hours to buy clothes, school supplies and computers without paying the 9.25 percent state and local sales tax.

Sara Jo Houghland, communications director for the Tennessee Department of Revenue, said the tax holiday typically saves customers in the state $8 million to $10 million.

"The local governments will be reimbursed for the weekend," Houghland said. "Tennessee has a 7 percent sales tax, but Hamilton County will get back the 2.25 percent tax that it loses. This is something that has been built into the budget."

Georgia shoppers, meanwhile, must cross the state line to get tax savings, because state officials canceled its tax-free weekend because of a budget crunch.

Well aware of what's going on down south, Chattanooga vendors are calling in all their employees to prepare for the expected influx of Georgia shoppers.

Bracing for crowd

Chris Hayden, manager at the Radio Shack in Hamilton Place, said cancellation of the holiday in Georgia "was a big push for us."

"We got a lot of stores from our district in Georgia to ship additional products to us," he said.

Customers can buy any one of Radio Shack's laptops or notebooks and qualify for the tax exemption, he said.

Jeff Sisk, manager of Mac Authority in Hamilton Place, said his store began ordering for the tax-free weekend two weeks ago and since has pre-sold more than 200 computers.

Customers who bought the computers will be able to bring their receipt and wait in a second, shorter line to retrieve their devices and get their sales tax break, he said.

Although the iPad is predicted to be a big seller this weekend, Sisk recommends getting younger students another computer, possibly the MacBook Pro for $1,199, rather than the iPad at $499, because middle and high school students tend to be rougher with their book bags.

Store manager Pat O'Sullivan, at the Staples in Hamilton Place, said she expects more than 1,000 customers this weekend, compared to 850 during the tax-free weekend last year. On average, only about 400 customers come through the store each weekend, employees said.

O'Sullivan said her store would have all employees working this weekend and, because of the Georgia cancellation, the Hamilton Place and Hixson locations have "bulked up with products."

Hamilton Place has extended its hours, too. Stores will be open 9 a.m. to 10 p.m. Friday and Saturday and 11 a.m. to 7 p.m. Sunday, said Catharine Wells, marketing director for the mall.

Win-win situations

Some stores are combining the holiday with an extra discount for what Houghland calls a "win-win situation."

Betty Pittard, store manager of Strasburg Children in Hamilton Place, said she is hoping customers will come in to take advantage of the tax-free holiday as well as a special promotion to help the area's less-fortunate children.

Customers who bring in two school supplies will get $10 off the cost of their purchase, she said. For three items, customers will get $15 off their purchase and, for four items, get $20 off purchases, Pittard said.

Pittard said the supplies - she requests pencils, loose-leaf paper, and crayons in particular - will go to homeless children at the Chattanooga Community Kitchen.

"It's all about the needy children, the homeless children, and making them feel like they are special and that we love them and care about them," Pittard said.

Employees at The Athletic Shop on Dayton Boulevard said customers could take advantage of 20 percent off regularly priced items in the store in addition to the tax exemption on school clothes.

Growing room

In what Rep. Jason Mumpower, R-Bristol, described as a "short-lived fight" among legislators, the Tennessee Legislature agreed to keep the tax-free weekend this year. Some legislators said the holiday should be canceled because of the state's budget crunch and sagging revenues.

But besides some state legislators, there are others who oppose the tax break, including The Tax Foundation, a nonpartisan tax research group based in Washington, D.C..

"Sales tax holidays introduce unjustifiable government distortions into the economy without providing any significant boost to the economy," according to a report put out by the foundation.

Mumpower sponsored the Tennessee bill and said parents, in particular, support the event. The law making a tax-free holiday came into effect in 2006. However, even Mumpower says there still is room for improvement concerning what is exempt and what is not.

"Unfortunately, our tax code is not perfect," he said.

Houghland at the state Department of Revenue said legislators would have to change the law to change which items are tax-exempt during the holiday.

According to the sales tax holiday website, items that do not qualify for the exemption include printers and ink, blank CDs, maps and reference books.