You have to put a letter on the following to make it a meaningful word. The only challenge is that you can't use 'E'.

S E Q U E N C _

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

I know there are two methods by using three time the same number with a plus(+) operator , you can make sum as 60.

One of them is 20+20+20.

whats the other way ?

Only one color, but not one size,
Stuck at the bottom, yet easily flies.
Present in sun, but not in rain,
Doing no harm, and feeling no pain.
What is it?

What is the centre of gravity?

What question can you never answer yes to?

Find out a multi-digit number that if multiplied by the number 9 or any of its multiplications products (i.e. 18, 27, 36, 45,..) will result in the multiplication factor repeated (n) number of times.

what does the below math rebus puzzle mean?

Can you place six matchsticks in a manner that each of the matchsticks is in touch with the other five matchsticks?

Why do you find that most of the buildings are deprived of the 13th floor?