word chain

123456789101112131415
Across
  1. 3. Space taken up by a 3D object
  2. 6. How many number in a number
  3. 10. Every decimal have got
  4. 12. To calculate or to judge the value
  5. 14. 7-2=5 in this case 7
  6. 15. Parallelogram with all sides of equal length
Down
  1. 1. The Angle is less than 90 degrees
  2. 2. Two lines don't have the intersection point
  3. 4. A lot of points
  4. 5. Middle number
  5. 6. The two lines intersect at 90 °
  6. 7. The bottom edge side of a graph
  7. 8. To discover,to get
  8. 9. Space covered inside a circle
  9. 11. Have three angles
  10. 13. To prove,to explain,to guide