St Ives
How many were going to St Ives?
Problem
You might have heard this riddle before, which is from the 18th century:
As I was going to St Ives, I met a man with seven wives, Each wife had seven sacks, Each sack had seven cats, Each cat had seven kittens: Kittens, cats, sacks, and wives, How many were going to St Ives? |
In this problem, we'll be assuming that everybody in the riddle is going in the direction of St Ives. Have a go at estimating the answer to the riddle. Roughly how many kittens, cats, sacks and wives do you think were going to St Ives?
Once you've estimated it, calculate the exact answer. How does this answer compare to your estimate? What do you notice?
Next, make up your own riddle like this for someone else to solve. (Remember to work out the answer so you can tell them if they're right or not!)
Teachers' Resources
Why do this problem?
This problem provides an opportunity for learners to practise multiplying large numbers by 7 within the context of solving a puzzle.
Possible approach
Allow some time for learners to tackle the St Ives problem as stated. The second part of the problem should be straightforward once they've finished the first part, as children should (hopefully!) be able to look back through their workings to find out which power of 7 is incorrect in the table.
Key questions
How many sacks/cats/kittens is that? What could you do to find out?
Can we draw a diagram of what's happening to make it clearer?
Possible support
Some children will need support with the multiplication, and might benefit from having access to a multiplication grid if they aren't confident with their 7 times table.
Possible extension
Children might like to make up their own riddles, as suggested in the final question on the problem page. Encourage them to stick to the formula by choosing a multiplication table and going up in powers of that table. Learners can be challenged to make up a riddle with fewer 'steps' where the answer is larger than that of the original, or to make up a riddle with more 'steps' where the answer is smaller.
Some similar activities involving repeated doubling are Sissa's Reward and Magic Potting Sheds.