You are here
Question 2 - Page 130 - Digital Roots - Chapter 5 Class 8 - Number Play (Ganita Prakash)
Last updated at January 8, 2026 by Teachoo
Class 8 (Ganita Prakash - 1, 2 & Old NCERT)
Chapter 5 Class 8 - Number Play (Ganita Prakash)
- Sum of Consecutive Numbers
- Parity of Arithmetic & Algebraic Expressions
- Pairs to Make Fours
- Factors and Multiples
- Always, Sometimes, or Never
- What Remains?
- Figure it out - Page 122, 123
- Divisibility Rules - 2, 5, 10 and 3
- Shortcut for Divisibility by 9
- Figure it out - Page 126
- Shortcut for Divisibility by 11
- Divisibility Shortcuts for Other Numbers
-
Digital Roots
- Figure it out - Page 131
- Digits in Disguise
- Figure it out - Page 132, 133, 134
Transcript
Question 2 - Page 130 Write the digital roots of any 12 consecutive numbers. What do you observe? Let’s pick numbers 12 consecutive numbers starting from 10 So, 12 consecutive numbers are 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 Finding digital roots for each For 10, Digital root is 1 + 0 = 1 For 11, Digital root is 1 + 1 = 2 For 12, Digital root is 1 + 2 = 3 For 13, Digital root is 1 + 3 = 4 For 14, Digital root is 1 + 4 = 5 For 15, Digital root is 1 + 5 = 6 For 16, Digital root is 1 + 6 = 7 For 17, Digital root is 1 + 7 = 8 For 18, Digital root is 1 + 8 = 9 For 19, Digital root is 1 + 9 = 10 → 1 + 0 = 1 For 20, Digital root is 2 + 0 = 2 For 21, Digital root is 2 + 1 = 3 Thus, we observe that Digital roots repeat in a cycle from 1 to 9 (1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 2, 3...).
