Find the square of 276 and 349 by the diagonal method.

1) Add each diagonal from bottom to top [Add the carry to next diagonal]

6 = 6

2 + 3 + 2 = 7

2 + 4 + 9 + 4 + 2 = 21 = 1 [take 2 to next diagonal]

1 + 4 + 4 + 4 + 1 + (2) = 16 = 6 [take 1 to next diagonal]

1 + 4 + 1 + (1) = 7

0 = 0

2) Now, write the result as digits obtained in step 1, from bottom to top.

i.e. 276² = 76176

1) Add each diagonal from bottom to top [Add the carry to next diagonal]

1 = 1

6 + 8 + 6 = 20 = 0 [Take 2 to next diagonal]

7 + 3 + 6 + 3 + 7 + (2) = 28 = 8 [take 2 to next diagonal]

2+ 2 + 1 + 2 + 2 + (2) = 11 = 1 [take 1 to next diagonal]

1 + 9 + 1 + (1) = 12 = 2 [take 1 to next diagonal]

0 + 1 = 1

2) Now, write the result as digits obtained in step 1, from bottom to top.

i.e. 349² = 121801