Solving with cubes, Strange!

How many cubes measuring 2 units on one side must be added to a cube measuring 8 units on one side to form a cube measuring 12 units on one side?


The answer is 152.

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12 solutions

Parth Lohomi
Sep 8, 2014

8x8x8(single cube)=512 c m 3 cm^{3}

let total number of 2 2 2 2*2*2 cubes be ''a''

then :- 8 a + 512 8a+512 = 1728 1728

8a=1216

a= 152 \boxed{152 }

more precisely : ( 1 2 3 8 3 ) / 2 3 (12^3-8^3)/2^3 => 152

Syed Hissaan - 4 years, 3 months ago
Tijmen Veltman
Sep 8, 2014

Equivalently, we can calculate the number of 1 × 1 × 1 1\times 1\times 1 cubes we need to add to a 4 × 4 × 4 4\times 4\times 4 cube to form a 6 × 6 × 6 6\times 6\times 6 cube, which is equal to 6 3 4 3 = 216 64 = 152 6^3-4^3=216-64=\boxed{152} .

Harshit Joshi
Sep 8, 2014

2x2x2 will have 8 cubes,

8x8x8 will have 512 cubes,

12x12x12 will have 1728 cubes,

so (1728-512)/8=152

Hon Ming Rou
Sep 8, 2014

8 8 8 = 512

12 12 12 = 1728

1728 - 512 = 1216

2 2 2 = 8

1216 / 8 = 152

Marvin Kalngan
May 8, 2020

Let m m be the number of 2 × 2 × 2 2 \times 2 \times 2 cubes needed, then

m = 1 2 3 8 3 2 3 = 152 m=\dfrac{12^3 - 8^3}{2^3}=\boxed{152}

volume of cube measuring 8 units

v8 = 8³ = 512 cubic units

volume of cube measuring 12 units

v12 = 12³ = 1728 cubic units

difference in volume

v12 - v8 = 1728 - 512 = 1216 cubic units

volume of cube measuring 2 units

v2 = 2³ = 8 cubic units

divide the difference in volume by the volume of cube measuring 2 units

1216/8 = 152 cubes

Matilda Belanno
Oct 8, 2015

How to do this if you're lazy and don't have a calculator:

1 2 3 × 8 3 2 3 \frac{12^3 \times 8^3}{2^3}
= 6 3 8 2 = 2 3 ( 3 3 2 3 ) = 6^3 - 8^2 = 2^3 (3^3 - 2^3)
= 8 × 19 = 8 × 20 8 = 8 \times 19 = 8 \times 20 - 8
= 160 8 = 152 . = 160-8 = \fbox{152}.


Rocel Polintang
Sep 30, 2014

To form 12x12x12 =1728 minus 8x8x8 =512 divide by 2x2x2=8

n= (12^3)-(8^3)=1216/8 = 152 :)

12x12x12=1728

8x8x8=512

2x2x2=8

1728-512=1216

1216/8=152

Christine Canedo
Sep 27, 2014

2^3=8 8^3=512 12^3=1728 2^3 x + 8^3 = 12^3 8x + 512 = 1728 8x = 1728-512 8x=1216 x=152

Christian Daang
Sep 27, 2014

(12 12 12)-(8 8 8) = 1216/(2 2 2) = 152

Ely Gangat
Sep 11, 2014

simply 2³x + 8³ = 12³

or x = (12³ - 8³)/2³

x = 152

It's wrong.

1 2 3 8 3 = ( 12 8 ) ( 1 2 2 + ( 12 8 ) + 8 2 ) 12^3 - 8^3 = (12 - 8)(12^2 + (12*8) + 8^2) = 4 ( 144 + 96 + 64 ) = 4 (144 + 96 + 64) = 4 ( 304 ) = 4 (304) = 1216 = 1216

( 1 2 3 8 3 ) / 2 3 = 1216 / 8 (12^3 - 8^3)/2^3 = 1216/8 = 152 = \boxed{152}

Joeie Christian Santana - 6 years, 8 months ago

You must have put that middle line into a calculator incorrectly.

Matilda Belanno - 5 years, 8 months ago

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