This problem was created by Henry E. Dudeney and published in "Fireside Puzzles" in The Daily Mail on December 24, 1912.
Note about pre-decimal British currency: Before decimalisation, the pound (symbol £) was divided into 20 shillings, (symbol s) and each shilling into 12 pence (singular penny; symbol d), making 240 pence to the pound.
Usually, prices were written with a / (called a solidus) between the amounts. For example, a sum of four shillings and eight pence was written as 4/8, and pronounced "four and eight". An even sum of shillings, say six shillings, was written as 6/-. A sum of one pound, nineteen shillings, and eleven pence would be written as £1/19/11 and pronounced "one pound, nineteen and eleven".
Note about pre-decimal British coins:
British coins in circulation in Victorian times and the first half of the twentieth century are: The farthing, worth ¼d, the half penny, worth ½d, the penny, worth 1d, the three pence, worth 3d, the six pence, worth 6d, the shilling, worth 1/, the florin, worth 2/, the half crown, worth 2/6, the crown, worth 5/, the half sovereign, worth 10/, and the sovereign, worth £1.
Maud and Christine went into a shop, where, through some curious eccentricity, no change was given, and their joint purchases of Christmas presents amounted together to less than five shillings. "I find," said Maud, "that I shall require no fewer than six current [as of 1912] coins of the realm to pay for what I have bought."
Christine thought a moment and then exclaimed, "By a strange coincidence, I am in exactly the same difficulty!"
"Then we will pay the two bills together." But, to their astonishment, they still required six coins. What is the smallest possible amount of their purchases—both different.
Maud's purchase amount:
Christine's purchase amount:
If you need to enter fractions of a penny, for example 1½d, you can type "1 1/2". Solutions can also be written as decimals if required.
You may enter the two amounts in either order.
The two purchases amounted to 1s. 5¾d. and 1s 11½d., and their sum to 3s. 5½d. Not one of these three amounts can be paid in fewer than six current [as of 1912] coins of the realm.
URL: http://www.allfunandgames.ca/classics/christmasshopping.shtml.Last update: August 16, 2010.