Question

Find out the larger product of each pair below, without actual multiplication.
$25\times 75$, $26\times 74$
$76\times 24$, $74\times 26$

Answer 1

$25\times 7526\times 74=(25+1)(75-1)=25\ast 75+75-25-1=25\ast 75+49$

So, $25\times 75<26\times 74$

$76\times 2474\times 26=(76-2)(24+2)=76\ast 24+76\ast 2-48-4=76\ast 24+100$

So, $76\times 24<74\times 26$