How many cubes are in the 10th collection of cubes in this sequence?
1st- 1 cube
2nd- 4 cubes
3rd- 10 cubes.....
l
l
l
10th- ? cubes
Any help appreciated!
Hello phillyfan09The sequence 1, 4, 10, ... is sometimes called Tetrahedral Numbers. Here's the answer to your question: Tetrahedral number - Wikipedia, the free encyclopedia.
Grandad
Hello, phillyfan09!
Where did this problem come from?
It doesn't give enough information to allow us a good guess.
Lucky for us, Grandad recognized the sequence.
How many cubes are in the 10th collection of cubes in this sequence?
. .
Imagine a display of oranges, stacked in a triangular pyramid (tetrahedron).
. . Each horizontal level is an equilateral triangle.
And we want the 10th Total on this list.
You can crank out the numbers yourself, or you can use this formula:
. .
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
By the way, this formula answers the question:
How many gifts did My True Love Give To Me
. . during the Twelve Days of Christmas?
. .