6th February 2004 at 00:00
Age 6-8

Treasure chests

Use every number once.

Take a number from the first chest.

Add it to a number from the second chest.

Take the right answer from the third chest.

Now write your sum.

Repeat this until all the numbers are used up.


Age 14-16

The area of an inclined face of a square-based pyramid is equal to that of a square drawn on the vertical height of the pyramid.

What angle does the inclined face make with the base of the pyramid?

Brainteaser solutions from page 30

Treasure chests

9 + 8 = 17; 7 + 24 = 31; 18 + 17 = 35; 5 + 11 = 16; 14 + 13 = 27


The inclined face makes an angle of very nearly 52 LESS THAN with the base of the pyramid. The cosine of the required angle OPH is ap. The square on OH equals DOAB, so h2=ap. Using Pythagoras, in DPHA, HA2 = 2a2. In DOAH, OA2 = h2 + 2a2 = ap + 2a2. in DOAP, OA2 = p2 + a2.

So a2 + ap - p2 = 0. Dividing through by p2, and solving for ap, gives ap approximately 0.62. Angle OPH is therefore just under 52 LESS THAN .

Subscribe to get access to the content on this page.

If you are already a Tes/ Tes Scotland subscriber please log in with your username or email address to get full access to our back issues, CPD library and membership plus page.

Not a subscriber? Find out more about our subscription offers.
Subscribe now
Existing subscriber?
Enter subscription number


The guide by your side – ensuring you are always up to date with the latest in education.

Get Tes magazine online and delivered to your door. Stay up to date with the latest research, teacher innovation and insight, plus classroom tips and techniques with a Tes magazine subscription.
With a Tes magazine subscription you get exclusive access to our CPD library. Including our New Teachers’ special for NQTS, Ed Tech, How to Get a Job, Trip Planner, Ed Biz Special and all Tes back issues.

Subscribe now