2015 Countdown Problem #23: A Log Cake for Christmas

Geometry Level 2

A family baked a log cake for Christmas which is cylindrical in shape. What is the largest possible number of pieces can the cake be divided to by making just three cuts with a straight-edge knife?

#MerryChristmas

This problem is part of the set 2015 Countdown Problems .


The answer is 8.

Wee Xian Bin by Wee Xian Bin , 25, Singapore

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

3 solutions

Jeff Chen
Dec 28, 2014

If every cut intersects every previous cut, it will always double the total number of pieces.

2 times 2 times 2 gives you 8

0 Helpful 0 Interesting 0 Brilliant 0 Confused

2 cuts lengthwise produce 4 pieces and then 1 cut horizontally produce 4*2 = 8 pieces

0 Helpful 0 Interesting 0 Brilliant 0 Confused
Madhav Srirangan
Dec 26, 2014

0 Helpful 0 Interesting 0 Brilliant 0 Confused

it should be 8 cut a cross of the log and then cut it in the middle lengthwise

Tanishq Varshney - 6 years, 5 months ago

can you make a picture where there are 3 cuts and 8 regions? i think the regions must be 7 at most, thanks :)

Justin Tuazon - 6 years, 5 months ago

Log in to reply

the answer 8 is correct. see my post above

Tanishq Varshney - 6 years, 5 months ago

Hint: Think in three dimensions :)

Wee Xian Bin - 6 years, 5 months ago

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...