A208646 Calendar Problem #27, April 2012 Mathematics Teacher.

9861, -1986, 9681, -1896, 8961, -1968, 8691, -1698

Offset: 1

Author

Jonathan Vos Post, Mar 01 2012

Keywords

• sign
• easy
• base

Comments

The numbers are paired on the basis of rotational symmetry with alternating signs.

Examples

			If you rotate the first number, 9861, 180 degrees about its center, and put a negative sign in front, you get the second number: -1986. Similarly, the third and fourth numbers are rotations of each other, as well as of the fifth and sixth numbers.  Therefore the eighth number is the rotation and negation of the seventh number, 8961, which would be -1698.
		

Links

• Margaret Coffey, Editor, Calendar Problem #27, April 2012 Mathematics Teacher, pp. 521, 524.

Crossrefs

Cf. A045574, A054047.