This book was used by my grandpa first with a slide rule, then with a 4 banger calculator to do math for designing radios he built himself from scratch (made his own inductors, metal boxes, and obtained every part via scrap)
Anyway most modern calculators that are capable of doing trig, and logarithms are still using this book in the form of a lookup table stored in the calculators Rom
Back in the day you'd substitute sin(#) for the closest matching number found in this book (it's listed in degrees and minutes of degrees)
The book was published in 1938 for Ontario schools so students could do trig, logs and compounding interest.
My grandpa likly used this and specialized slide rules till the mid to late 80s. (LC tank circuit/inductor winding slide rule, ohms law slide rule, parallel/series resistor slide rule, and a generic math slide rule)