What is always in front of you but can’t be seen?

What is the next number in this series?

4,12,84,3612....

I live in a bowl. I can swim. I have a tail. I also have fins and big eyes. What am I?

Given below is simple addition with a defined pattern pattern:
7 + 7 = 2
8 + 8 = 4
8 + 5 = 1
6 + 9 = 3
10 + 11 = 9

Can you analyze the pattern and find out the answer for:

4 + 9 = ?

There is a hypothetical state between the USA and Mexico border 'Tango'.
Here 70 percent of the population have defective eyesight, 75 percent are hard of hearing, 80 percent have Nose trouble and 85 percent suffer from allergies, what percentage (at a minimum) suffer from all four ailments?

You need to move three matchsticks to form three squares. Can you do it?

Find three whole, positive numbers that have the same answer when multiplied together as when added together.

A girl is twice as old as her brother and half as old as her father. In 50 years, her brother will be half as old as his father. How old is the daughter now?

A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?

Can you count the number of lines in the below picture?