Question 427819


45*55 

we can write, 45 = 50 -5 and 55 = 50+5

so, 45*55

=(50-5)(50+5)

= (50)^2 - (5)^2

= 2500- 25

= 2475

as we know, (a-b)(a+b) = a^2 -b^2