Class 8 Maths - KARNATAKA
Number Play
The chapter 'Number Play' in Class 8 Mathematics for Karnataka (KSEEB) students dives into the fascinating world of numbers, puzzles, and patterns. It introduces students to writing numbers in their general or expanded form using letters like a, b, and c to represent digits. You will learn the rules behind divisibility tests for numbers such as 2, 3, 5, 9, and 10, helping you check whether a number is divisible without actual division. This chapter strengthens logical reasoning and problem-solving skills, which are frequently tested in board exams through word puzzles and numerical riddles.
Start Learning FreeKey Concepts
General Form of Numbers
A two-digit number like ab can be written in its expanded form as 10a + b, where 'a' is the tens digit and 'b' is the units digit.
Reversing Digits
When the digits of a two-digit number ab are reversed, the new number becomes ba, which is expressed algebraically as 10b + a.
Divisibility by 9 and 3
A number is divisible by 9 (or 3) if the sum of its digits is a multiple of 9 (or 3).
Divisibility by 10, 5, and 2
A number is divisible by 10 if its units digit is 0, by 5 if its units digit is 0 or 5, and by 2 if it is an even number.
Puzzles with Letters
Arithmetic puzzles where letters take the place of digits, and you must use rules of addition and multiplication to find the hidden digits.
Important Formulas
Board Exam Info
In the Karnataka (KSEEB) Class 8 mathematics examinations, 'Number Play' typically carries around 4 to 6 marks. Questions usually appear as 1-mark objective divisibility checks, 2-mark simplification problems based on general forms of numbers, and 3-mark puzzle-solving word problems where students must find the missing digits.
Frequently Asked Questions
Why do we write numbers like 10a + b instead of just ab?
Writing ab looks like a product (a multiplied by b). The form 10a + b correctly shows the place value of the digits in a two-digit number.
How do I solve letter arithmetic puzzles in exams?
Start by looking at the units column to find clues about possible digit values, keeping in mind that each letter represents a single digit from 0 to 9.
Are divisibility rules applicable to negative numbers?
For Class 8 KSEEB syllabus, divisibility rules are primarily applied to positive integers and whole numbers.
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