# Riddle me this: how can 68 + (3x1) = 70?

**URL:** <https://boards.straightdope.com/t/riddle-me-this-how-can-68-3x1-70/105306>\
**Category:** Cecil's Columns/Staff Reports\
**Created:** [April 24, 2002, 6:37am UTC](https://boards.straightdope.com/t/riddle-me-this-how-can-68-3x1-70/105306 "2002-04-24T06:37:07Z")\
**Posts on this page:** 4\
**Page:** 3

<div class="post-metadata">

**Author:** ![Jbone](https://avatars.discourse-cdn.com/v4/letter/j/58f4c7/32.png) [@Jbone](https://boards.straightdope.com/u/Jbone)\
**Post date:** [November 28, 2012, 7:18pm UTC](https://boards.straightdope.com/t/riddle-me-this-how-can-68-3x1-70/105306/41 "2012-11-28T19:18:13Z")

</div>

Realistically, I doubt any pedestrian bridge would collapse with one extra kilogram of weight, so, he just walked across the bridge without any problems.

If there was a strict 70 kilo limit, and he did have to carry the pieces on his person (not twirling around his head, or juggling, or any sort of other way people have come up with as a workaround), I think a several-day crash diet, shedding of clothing, or amputation(if he absolutely needs to get across) would be some of the only valid ways.

I would stick with the crash dieting and wait it out myself.

---

<div class="post-metadata">

**Author:** ![WildSage](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WildSage](https://boards.straightdope.com/u/WildSage)\
**Post date:** [November 29, 2012, 1:10am UTC](https://boards.straightdope.com/t/riddle-me-this-how-can-68-3x1-70/105306/42 "2012-11-29T01:10:47Z")

</div>

> [@gamerunknown](#):
>
> If he has a rope of sufficient length, he can just string it up so that it’ll enter the bridge as he exits it. Assuming there are no bandits that’ll pounce and cut the rope, taking the gold.

Quoted directly from the original question: “How does he cross the bridge safely, without throwing or dragging the gold across?”

---

<div class="post-metadata">

**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\
**Post date:** [November 29, 2012, 2:44am UTC](https://boards.straightdope.com/t/riddle-me-this-how-can-68-3x1-70/105306/43 "2012-11-29T02:44:04Z")

</div>

> [@Powers](#):
>
> It will only be balanced (I assume you’re referencing Newton’s Third Law) if the bridge doesn’t collapse, which it will because the whirlygig is pushing down on it.
> 
> I mean, you couldn’t send an elephant across and say that its not exerting a downward force on the bridge just because Newton’s Third Law says there is an equivalent upward force on the elephant.

The upward force on the whirly-gig comes from the air it is blowing down. The downward force on the air is not all on the bridge. Since the whirly-gig is supported by the air, not the bridge, it’s not contributing its full weight to the bridge.

Unlike an elephant, if a helicopter flies over you, it doesn’t crush you. It’s weight is distributed over a wide area, not just straight below it.

---

<div class="post-metadata">

**Author:** ![gamerunknown](https://avatars.discourse-cdn.com/v4/letter/g/6bbea6/32.png) [@gamerunknown](https://boards.straightdope.com/u/gamerunknown)\
**Post date:** [November 29, 2012, 7:38am UTC](https://boards.straightdope.com/t/riddle-me-this-how-can-68-3x1-70/105306/44 "2012-11-29T07:38:36Z")

</div>

> [@WildSage](#):
>
> Quoted directly from the original question: “How does he cross the bridge safely, without throwing or dragging the gold across?”

Oh, I was wondering if there were a condition I missed. What about loading the gold onto a remote controlled car?

[Previous page](https://boards.straightdope.com/t/riddle-me-this-how-can-68-3x1-70/105306.md?page=2)