## 1.) How many triangles do you see this picture ?

### Answer with solution

**How?**

Let’s say the smallest triangle side is 1 cms, then

**Number of triangles with side 1cms**: 10(1+2+3+4 upward facing) + 6(0+1+2+3 downward facing)

**Number of triangles with side 2cms**: 6(1+2+3 upward facing) + 1(downward facing)

**Number of triangles with side 3cms**: 3(upward facing)

**Number of triangles with side 4cms**: 1(upward facing)