+0

# Magic Penny Parable

0
149
2

Suppose you stacked pennies after 22 days. How high would the stack rise, in kilometers?

Guest Mar 13, 2017
Sort:

#1
+89749
0

Suppose you stacked pennies after 22 days. How high would the stack rise, in kilometers?

I assume you mean you stack 1 penny the first day, add 2 the second day, add 4 the third day.  etc

$$1+2+4+ .... 2^{k-1}.........+ 2^{22-1}\\ \boxed{S_n=\frac{a(r^n-1)}{r-1}}\\ S_n=\frac{1(2^{22}-1)}{2-1}\\ S_n=2^{22}-1\\$$

I found this on the web i assume it means a penny is 1.52mm thick.

The United States one- cent coin oft called penny , is a unit of currency equaling ... The coin is 0.75 inches (19.5 mm) in diameter and 0.0598 inches (1:52 mm) in thickness .

((2^22-1)*1.52)/(1000*1000) = 6.37534056

So that is approximately 6.4 kilometres

Melody  Mar 13, 2017
#2
+32
+5

2x22=44

44x1.52=1672/25

1672/25=66.88 Milimeters

66.88 mm= 0.00006688 Km

ZerpMerp  Mar 13, 2017

### 13 Online Users

We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details