# Number magic - math puzzle

If you multiply me by 2, subtract 1, and read the reverse the result you'll find me. Which numbers can I be?

# Apple - math puzzle

Eric has a perfect spherical shaped apple. With a cilindrically shaped drill bit he removes the core of the apple. A cilindrically shaped hole remains, the center of this hole is exactly at the center of the apple. Eric measures the length of the hole with a piece of rope. It turns out to be exactly 8 cm. What is the volume of the remaining apple? |

# Straight line sum - math puzzle

Correct the equation above by inserting one straight line.