Practice Book On - Quicker Maths

It sounds like you're looking for a sample piece — possibly an introduction, a chapter outline, or a review — for a book titled

[ (100 + d)^2 = 10000 + 2 \times 100 \times d + d^2 ] Practice Book on Quicker maths

Below is a short, original piece written in the style of a preface + sample exercise section for such a practice book. “Quicker Maths” is not about skipping steps — it’s about choosing the shortest reliable path. In competitive exams, time is the real opponent. This practice book is designed for those who already know the basics but want to solve problems faster, cleaner, and with fewer errors. It sounds like you're looking for a sample