2. Take out a 3*3 square from the March calendar. It is known that the sum of the three small squares on the diagonal is 24. What's the date of March in the middle square?

The square in the middle of the square is March X.

(X-8)+X+(X+8)=24 or (X-6)+X+(X+6)=24.

X=3

3. The sum of two natural numbers is equal to 352, and the last digit of a number is 0. If this "0" is erased, it will be the same as another number. Find these two numbers.

Set another number x.

10*X+X=352

X=32

These two numbers are 32 and 320.

53X( 1/23- 1/76)-76( 1/23- 1/53)-23X( 1/53+ 1/76)

=(53-76)* 1/23+(53+23)* 1/76+(76-23)* 1/53

=- 1+ 1+ 1

= 1