Fast/Quick Calculations in Math

Here is some Fast/Quick Calculations in math.
1) Square
Q1-Square of Rs. 110 . solution is as under
First step :- 110-100 =10 now 10 is important
Add 10 in 110 i.e. 110+10 =120
& Square of 10 i.e. 10 x 10 =100
Final Step :- 120?? +100= 12100 is answer
Q2- Square of 95
First step :- 95-100 = -5 now -5 is important
Add -5 in 95 = 95 -5 = 90
& Square of -5 = -5 x -5 = 25
Final Step :- 90??+25 =9025
2 Sum:-
Q1-Sum of 1 to 100 is very simple. no need to use calculator.
100 and its next amount which is 101 is important in this case
(100 x 101)/2 is answer. = 5050
Q-2 Sum of 1 to 75
Answer = (75 x 76)/2 =2850