Question

First guess the answer and then check it by calculating:
$42\times 23=?$

Answer 1

Guessing method:

$42\times 23=42\times 20=840$

Actual Calculation:

$42\times 23$

$=42\times (20+3)$

$=(42\times 20)+(42\times 3)$

$=840+126$

$=966$