Question

square of 42 without actual multiplication

Answer 1

Here is the solution :

We know that,
(a+b)² = a² + 2ab + b²,

Now let a = 40,
and b = 2,

Substituting them in the above formula,

=> (40+2)² = 40² + 2*40*2 + 2²
=> 42² = 1600 + 160 +4
=> 42² = 1764,

Therefore : Square of 42 = 1764,
Proved without Actual multiplication.

Hope you Understand, Have a Great day !
Thanking you, Bunti 360 !!

Answer 2

The square of 42=(40+2)^2=1600+160+4=1764[using the formula (a+b)^2=a^2+2ab+b^2]
If you want trick then it is
_ _ _
in the last _ put the value of the square of the last digit of the number whose square is to be taken=2^2=4( if there is a two digit number take the ten's digit as handover to the next digit)
_ _ 4

in the second _ enter the product of 2 , the first digit(of the number whose square is to be taken) , and the last digit ( of the number whose square is to be taken)
=2*4*2=16(take the ten's digit so obtained here as the handover to the next digit(here it is 1))
_ 64

in the first digit here enter the square of the first digit of the number (of the number whose square is to be taken)(here it is 4^2 and handover 1=16+1=17)
1764 and thats the answer
Hope I Helped You!