274 CALCULATING PRODIGIES [CH. XIII 



2 hours 1 minute 56 seconds, each year containing 365 days 

 5 hours 48 minutes 55 seconds: answer, 2,165,625,744| inches, 

 given in less than a minute. If I have 42 watches for sale and 



1 sell the first for a farthing, and double the price for every 

 succeeding watch I sell, what will be the price of the last watch: 

 answer, £2,290,649,224. 10s. 8d. If the diameter of a penny 

 piece is If inches, and if the world is girdled with a ring of 

 pence put side by side, what is their value sterling, supposing 

 the distance to be 360 degrees, and a degree to contain 695 

 miles: answer, £4,803,340, given in one minute. Find two 

 numbers, whose difference is 12, and whose product, multiplied 

 by their sum, is equal to 14,560 : answer, 14 and 26. In 1819, 

 when fourteen years old, he was asked : — Find a number whose 

 cube less 19 multiplied by its cube shall be equal to the cube 

 of 6 : answer, 3, given instantly. What will it cost to make 

 a road for 21 miles 5 furlongs 37 poles 4 yards, at the rate 

 of £123. 14s. 6d. a mile : answer, £2688. 13s. 9f d, given in 



2 minutes. If you are now 14 years old and you live 50 years 

 longer and spend half-a-crown a day, how many farthings will 

 you spend in your life: answer, 2,805,120, given in 15 seconds. 

 Mr Moor contracted to illuminate the city of London with 

 22,965,321 lamps, the expense of trimming and lighting was 

 7 farthings a lamp, the oil consumed was fths of a pint for 

 every three lamps, and the oil cost 3s. I^d. a gallon ; he gained 

 16 J per cent, on his outlay: how many gallons of oil were 

 consumed, what was the cost to him, and what was the amount 

 of the contract : answer, he used 212,641 gallons of oil, the cost 

 was £205,996. 16s. lfd., and the amount of the contract was 

 £239,986. 13s. 2d. If the distance of the earth from the moon 

 be 29,531,531 £ yards, what is the weight of a thread which 

 will extend that distance, supposing 7{£ yards of it weigh -^th 

 part of a drachm : answer, 8 cwt. 1 qr. 13 lbs. 9 oz. 1 dr. and 

 |f ths of a drachm. 



It should be noted that Bidder did not visualize a number 

 like 984 in symbols, but thought of it in a concrete way as so 

 many units which could be arranged in 24 groups of 41 each. 

 It should also be observed that he, like Inaudi whom I mention 



