Book I can't let go: Collins Essential Calculator

Condition: good

Inscribed, in ink:
To Ken, so you can make billions and billions in the Mediterranean sun.
Yolande
4/7/81
Weybridge

Probably bought by my father at a jumble sale or church fête within a four-mile radius of Weybridge. So much for the sun. I expect Ken had a calculator.

Published 1975, first and presumably last edition.

Content: computer-set tables for multiplication, division and percentages, including profit percentage on sales or mark-up.  Goes up to 99 x 1050 and 60% margin. 

Some worked examples are provided. 'It takes 77lbs of sand to cover 1 sq. yard. How much sand is required to cover 640 sq. yards?' Answer in tons, please.

Brexiter cult value: high. Salutes imperial measurements and outdated drudgery; ignores need to be competitive in today's market.

Reason for keeping: misplaced nostalgia for a totem of certainty.