The sum of the first 20 terms of the series $$\frac{1}{5×6}+\frac{1}{6×7}+\frac{1}{7×8}+...$$​ is:

12 numbers are in arithmetic progression. Average of first and last number of this progression is 16. What is the average of these 12 numbers?

6 + 12 + 18 + 24 + ....... +612 = ?

All pillars of street light was installed in a straight line at a distance of 50 meter(m) interval. What will be the distance between first and ninth pillar ?

Find the sum of all three-digit numbers divisible by 9 .

Next number in the series 1, 50, 100, 5000, 10000, ___ is :

On simplification, 1 - 2 + 3 - 4 + 5 - 6 + 7 - 8 +  _____+ 111, we get

The sum of 21 + 22 + 23 + .....+ 50 is

1 + 2 + 3 +………+ 50 equals

On simplification 1 – 2 + 3 – 4 + 5 – 6 - - - - + 101, we get

If 1² + 2² + …. + 9² = 285, then the value of (0.11)² + (0.22)² + … + (0.99)² is -