Dating Made Easier

If a sum invested gains 10

If an object depreciates in value by 10

Why aren’t these two answers the same?

Is there a rate, used for both gain and depreciation, for which those two answers would actually be the same?

See the notes for teachers and solution 

See the DATING MADE EASIER poster.

This activity is adapted from the NRICH task Dating Made Easier with permission of the University of Cambridge. All rights reserved.