arryputtar wrote:

29^2 how to solve this ?

Step 1: Identify the digits

29 - lets say "2" as "a" and "9" as b

So 2-> a and 9-> b

Step 2: Plug into the equation below

a^2 | 2(a*b) | b^2

instead of a -> use 2 and instead of b-> use 9

Step 3:

So by plugging in we get

2^2 | 2(2*9) | 9^2

Step 4:

solve the thing

2^2 => 4

2(2*9) => 36

9^2 => 81

4 | 36 | 81

Step 5:

this is the kewlest thing....all you need to do is carry over from right to left

4| 36 | 81 -> carry over 8 (left most digit just like addition)

4| 36 + 8 | 1 => 44 | 1

now from 44 carry over 4

4 + 4 | 4 | 1

8 | 4 |1 => 29 ^ 2 => 841

Fortunately we rarely (probably never) need to square awkward large numbers on the GMAT. If I need to find the value of 29^2, I'd take advantage of the difference of squares:

29^2 - 1 = (29 + 1)(29 -1) = (30)(28) = 840

so 29^2 = 841.

This would be a fast approach for a number ending in 9 or 1; for other numbers it would still lead to an awkward calculation.

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