IN THE SHOP
Instantly find the change due from £10 or £20
- Suppose you buy something for £3.33 and you
give a £10 note. How much change would you
you expect to get?
You just apply ALL FROM 9 AND THE LAST
FROM 10 to the £3.33 and you get £6.67
- £10 - £2.30 = £7.70
Here “the last” is the 3 as zero does not count.
So we take 2 from 9 and 3 from 10.
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In The Shop
Zerah Colburn (1804-40), when he was eight,
was asked to raise the number 8 to the sixteenth
power: he announced the answer
(281,474,976,710,656) "promptly and with
facility",causing the academic audience to
weep. He was next asked to raise the numbers
2,3,....9 to the 10th power: and he gave the
answers so rapidly that the gentleman who was
taking them down was obliged to ask him to
repeat them more slowly.