Class 8 · Chapter 5
Number Play
Number puzzles, divisibility, and digit patterns.
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Ganita Prakash · Class 8 Part 1 (2026-27)
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Latest 2026-27 edition on ncert.nic.in
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Tip: NCERT updated the syllabus for 2026-27. The links above open the latest edition on the official portal — chapter titles and numbering may differ from the notes shown here.
Detailed theory
Divisible by 6 = by 2 AND 3. By 12 = by 3 AND 4. Combining rules speeds up checks.
Key concepts & formulas
01
Divisibility rules for 2, 3, 4, 5, 6, 8, 9, 10, 11.
02
Digit sums for 3 & 9.
03
Alternating digit sums for 11.
04
Cryptarithms replace digits with letters — decode using divisibility.
05
Reverse-and-difference: any 2-digit reversed diff is divisible by 9.