* Approximately 50,000 people were employed to construct the canal.

Two-thirds of these were black West Indians and about 6,000 were white Americans. How many of those employed were neither white Americans, nor black West Indians?

* If $US600 million (pound;321 million) is 7 per cent of Panama’s gross domestic product, what is Panama’s GDP?

* How many cubic yards is there in a cubic metre?

* Estimate the mass of Earth and rock excavated. This will require an estimate of the average density of the excavated material and care will be needed with units.

* How much per tonne did the cruise ship Infinity pay to go through the canal? How does that tie in with the other figures about record tonnage per day and annual income?

* The average toll is $US28,000 (pound;15,000) and tolls yield a revenue of $US600 million (pound;321 million) per annum. How many ships is that? Does this agree with the information in the article? If not, what might be the reasons for the difference? This could lead to a discussion on types of average.

* The Panama canal brings to mind a famous palindrome: “A man, a plan, a canal, Panama”. Numbers that are palindromes can have interesting properties. For example, all palindromic numbers with an even number of digits, such as 24677642, are divisible by 11. An interesting exercise, suitable for Year 7 upwards, is to investigate why.

Charlie Stripp