Patterns designed to show changes by fifteen. Fifteen is a multiple used in time and angular measurement in degrees.
The number fifteen occurs with surprising frequency in a many every day situations. The ancient Babylonians used a base-60 numbering system that is carried on the ways we measure time as well as angles (in degrees) in geometry. Because of this, recognizing number patterns that are involve in 15 as a base unit is a useful skill. The number pattern worksheets on this page deal with fifteen in their rules and are great ancillary practice for math units that are working with time or geometry, or just general addition and subtraction skills.