Dear Dr. Gridlock:

In your column on Monday, June 28, you inquire what car was referred to by license plate 1 DIV 0. I believe it refers to an Infiniti, since when you divide 0 into 1 the result is infinity.

William H. Rehnquist

Chief Justice of the United States

Washington

Exactly. Dead on.

When Dr. Gridlock called Rehnquist's secretary, Janet Barnes, to verify this entry, she immediately asked, "Did he win?" There's no way, apparently, to overestimate the lure of these riddles.

So on to the next one, submitted by Jim Wyatt, of Nokesville:

Tell us what kind of car has been seen with the license plate: R PFERD.

This is not easy. Care to give it another go, Mr. Chief Justice?

Please, No Flossing

Dear Dr. Gridlock:

I read with interest the letter from a Tysons Corner reader who expressed concern with women putting on makeup while driving.

I ride the Orange Line from New Carrollton and sometimes get to watch a woman floss her teeth.

This happens after she's eaten her breakfast, also in front of passengers. Then I get to watch her put on her makeup or perform other personal grooming, like nail clipping.

Other women sometimes put on their makeup in the morning, and if that's all she did, I would never have noticed her. It's the eating/ flossing/clipping of nails and other quirks that make this woman stand out.

I know eating on the subway is against the law. Flossing should be illegal, too.

Karen Lee

Bowie

Flossing and nail clipping. That's over the line. How about a new federal law: No flossing across state lines?

In Defense of Makeup

Dear Dr. Gridlock:

In response to the Tysons Corner woman who complained about women applying makeup in traffic:

I drive 22 miles to work each day. Because I drive through the city, it takes anywhere from 60 to 90 minutes to complete my commute. The majority of my time is spent at traffic lights and sitting still in traffic jams.

I do apply makeup when sitting still and am amazed at those who honk horns and become hostile because I am using my time wisely.

If your neighbor in traffic is not creating a hazard and not bothering anyone, WHAT'S IT TO YOU?

Taryn Morgan

Bowie

A Shave, a Chat, a Map

Dear Dr. Gridlock:

Recently I was on the Beltway in Friday evening traffic when I saw a man shaving, talking on the phone and looking at a map spread across his steering wheel.

At 4:45 in rush hour traffic, the only thing I have time to do is watch out for other drivers. How on Earth can anyone have time to do anything else?

Catherine Power

Centreville

Woman on Wheels

Dear Dr. Gridlock:

A few years back, at a red light at Tysons Corner in morning rush hour, I watched a lady take out a full set of curlers, comb her fingers through her hair, and sport a perfect 'do' before the light turned green.

Wonder Woman couldn't have done much better.

Kristina Maze

Washington

This is our driving culture: automobile accidents that can be caused by reckless makeup application or failure to arrange hair properly.

Book me on a one-way trip, please, to Flamingo, that gridlock-free spot at the bottom of Florida's Everglades.

I-95 Entrance Ramp Closing

As part of the Springfield interchange reconstruction of Interstate 95, the eastbound Old Keene Mill Road ramp onto southbound I-95 will be closed after morning rush hour next Monday, July 19. This will continue for years to allow construction equipment access to the interstate. State officials advise travelers to detour south on Backlick Road to the Newington interchange, about 2.5 miles.

The ramp from eastbound Old Keene Mill Road to northbound I-395, I-95 and the Beltway will remain open.

Dr. Gridlock's assistant, Jessica Medinger, contributed to this column.

Dr. Gridlock appears Monday in the Metro section and on Wednesday or Thursday in the Weekly and Extra sections. You can write to Dr. Gridlock, P.O. Box 3467, Fairfax, Va. 22038-3467, or email him at drgridlock@washpost.com. The Doctor's fax number is 703-352-3908. Please include your full name, address and day and evening phone numbers.

CAPTION: Springfield Interchange Update (This graphic was not available)