But for numbers 20 through 80, they used a binary system, with separate, one-word terms for 20, 40 and 80. For really large numbers, they used powers of 10 up to at least 10 million.

Latest edition of NCERT Class 9 Maths Chapter 1 Number System is available here. Download the full chapter in PDF format along with the accurate NCERT Solutions for the chapter.

CBSE Class 9 Maths extra Questions for Chapter 1 - Number System (with Answers). These questions are NCERT based important for the preparation of the upcoming CBSE 9th Maths Exam 2020-21.