We found this old puzzle dating back to the 1970s and think it is quite interesting. And will give the youngsters an idea of the confusion during the change to decimal coins.
At the time of changeover some of the new coins replaced their corresponding old coins. So the two-shilling coin (24 old pennies) was replaced by a 10p coin; similarly the one-shilling coin (12 old pennies) was replaced by the 5p coin. These coexisted with the old coinage for a while - for example the sixpence (6 old pennies) was in circulation alongside the 5p and 10p coins.
It took a while to convert all the coin machines and for a time the drinks machine took 5p coins, the car park took 10p coins, but the phone box took only sixpences.
Someone took a £1 note (yes there was such a thing) into the Post Office to get change, and asked for a mix of 5p coins, 10p coins and sixpences. They received 13 coins.
£1 was 20 shillings or 240 old pennies - how many of each coin were given in change?
The only way that £1 can be split into 13 coins is eight 10p coins (worth 80p or 16 shillings), three 5p coins (worth 15p or three shillings) and two sixpences (worth 5p or one shilling).