A triangular recycling symbol or Resin Identification Code made of three arrows with the number three in the middle and the word "PVC" under.

Plastic Number Three Symbol 

The number three inside a circle, which could be a notification.

Number Three In A Circle

A smiling male baseball player with the number three on his shirt holding a bat horizontally and leaning back, as if he had just striked a ball.

A handwritten symbol of a square root next to the number three as blackboard content for math class.

Three cubes toys or blocks: one with a capital letter A, one with the number one and one with the number three.