Question

if six cubes of 20cm edge are joined end-to-end then the surface area of theresulting solid is

Answer 1

Just count the number of squares on the surface and multiply it by 20^2.

Answer 2

should we count the bottom square

Answer 3

which squares to count

Answer 4

Top, bottom,front, back, the two ends.
Count all exposed squares.

Answer 5

6 * 400 =2400 for one cube

Answer 6

they are joined end to end

Answer 7

10400?

Answer 8

But you might not want to calculate the surface area that way. First of all, do you agree that the resulting figure is a cuboid?

Answer 9

yes

Answer 10

It has the same width and the same height, but the length is six times.

Answer 11

2(bl+bh+hl) i got it thanks

Answer 12

Yes, you got it. That's correct.

Answer 13

6 cubes, with 4 exposed surfaces each = 24 exposed surfaces, plus 2 end surfaces for a total of 26 exposed squares which can be done mentally. 26 * 400 = 10,400 and is much simpler than using the formula 2(bl+bh+hl).

Answer 14

yup!