Question

Find the value of $(84{)}^3$ using the short-cut or column method:

Answer 1

${84}^3={(80+4)}^3$
It is in the form of ${(a+b)}^3$, where $a=80,b=4$
Applying the formula ${(a+b)}^3=a^3+b^3+3ab(a+b)$

${84}^3={(80+4)}^3={80}^3+4^3+3\times 80\times 4\times (80+4)$

$=512000+64+80640=592704$