(x-1)*(x+1) = x2 - x + x - 1 = x2 - 1
So, when x = 30,
29*31 = 30*30 - 1
Or, since 30*30 = 900, 29*31 = 900-1 = 899
One example is 1 + 899.
899
900
It is: 899+1 = 900
1-900 = -899
900
There are 900 centimeters in 9 meters, as 1 meter is equal to 100 centimeters.
To get the next number after any number, just add 1.
One less than 900 is 899.
The number is still 899, but it has been rounded to 1,000 .
It is: 30*30 = 900
30 x 30 = 900