Solution = 1
Let a = 123456789
Its x^2 - (x-1)*(x+1)
(x-1)*(x+1) = x^2 -1
=> x^2 - (x^2-1) i.e. 1
So answer is 1
1 ALWAYS works!
(n*n) - (((n-1)*(n+1)=1
With the numbers 123456789, make them add up to 100.
They must stay in the same order. (1 to 9)
You can use addition, subtraction, multiplication, and division.
If you are only allowed to press the 1 and 0 keys on a calculator with any of the add, take, times, divide and equals keys, what is the fewest number of presses needed to make the number 9 on the calculator?