How many triangles are there on the puzzle below?

Can you find a seven digit number which describes itself. The first digit is the number of zeros in the number. The second digit is the number of ones in the number, etc. For example, in the number 21200, there are 2 zeros, 1 one, 2 twos, 0 threes and 0 fours.

Using four sevens (7) and a one (1) create the number 100. Except for the five numerals, you can use the usual mathematical operations (+, -, x, :), root and brackets ()

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

A 3 digit number is such that it's unit digit is equal to the product of the other two digits which are prime. Also, the difference between it's reverse and itself is 396.

What is the sum of the three digits?

Solve the mathematical equation in the picture below.

Using Only Five 5's and any mathematical operator make sum as 37

Joseph buys three kinds of chocolates for 100 rupees. The first one is priced at 5 rupees, second one at 3 rupees and third one at 0.5 rupees.

If he bought 100 chocolates in total, how many pieces do you think he bought each chocolate?

What is next number in the pattern below:

131 517 192 123 ?

How many pluses should we put between the digits of 987654321 to get a total of 99, and where?