Explain how you can solve 8x8 if you know how to multiply with 4 but not how to multiply with 8

Turn the 8's into 4's and 2's:

8×8
4×2×4×2
4×4×4
16×4
64

Or just turn one of the 8's into 4 and 2
8×8
8×4×2
16×4 or 32×2
64

If you only know how to multiply with 4's, then you need to quickly convert the 8's to 4's.

We were given,



So we rewrite each of the 8's as



Perfectly for us,it turns out that the 2's will also give us a 4, so the whole thing becomes,





Now, let us multiply two of the 4's, to obtain,



Finally, let us multiply with the last 4 to get,

It would be 18 cm

We need more info then that