Triangle, Mathematical Riddle

Which is the number that is absent in the center of the
last triangle?

The House

One house has seven rooms; each of them is called like the weekdays: Monday, Tuesday… How can we call home?

What is it?

That thing you see in a minute, in a week and in a month and in a year is not.

The hunter

In a roof there is a nest with 20 birds; if a hunter shoots and kills 4. How many birds stay in the roof?

The book.

On having read a story, if you count of the page 78 up to the page 108, how many times you would find the number 8?

The Super-Tricycle!

About an hour ago I parked my super tricycle because I went to a shop to buy a car. When I went back, I didn´t remember what number did I parked it in. I need to find it!

Would you please help me?

What parking spot number is my super tricycle parked in?

NUMBERS

Try to find the similarity between this numbers, it is very easy.

5386=3

8568=5

1299=2

9569=3

1793=1

7513=0

3086=4

5729=1

2272=0

6791=2

8391=3

7102=???