Class 8 Maths - BIHAR
Number Play
The chapter Number Play in Class 8 Mathematics introduces students to the fascinating world of numbers through puzzles, riddles, and mathematical patterns. Bihar Board students will learn how numbers can be expressed in general forms, such as two-digit and three-digit numbers using their digits and place values. This chapter also covers interesting divisibility tests for 2, 3, 5, 9, and 10, helping students check calculations quickly. It builds strong logical reasoning and mental math skills, which are essential for solving higher-level arithmetic problems and scoring well in school examinations.
Start Learning FreeKey Concepts
General Form of a Number
Any 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 (10a + b) are reversed, the new number becomes ba (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.
Number Puzzles
Puzzles where letters take the place of digits in arithmetic operations, requiring logical deduction to find the correct values.
Important Formulas
Board Exam Info
In the Bihar Board Class 8 Mathematics examinations, Number Play typically carries around 4 to 6 marks. Questions usually include short-answer numerical puzzles, finding unknown digits in addition or multiplication riddles, and applying divisibility tests.
Frequently Asked Questions
Why do we write numbers in general form like 10a + b?
Writing numbers in general form helps us understand their algebraic structure, making it easier to solve number puzzles and prove divisibility rules.
How do I solve letter puzzles like A + B = C?
Start by analyzing the units column and place value carries. Test single-digit numbers from 0 to 9 that satisfy the given condition logically.
Is it compulsory to show steps in divisibility reasoning questions?
Yes, Bihar Board exams require you to show the sum of digits or the rule application clearly to get full marks.
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