Class 7 Maths - BIHAR
Number Play
The Chapter 'Number Play' in Class 7 Mathematics for the Bihar Board introduces students to the fascinating world of numbers through puzzles, riddles, and mathematical patterns. It focuses on understanding numbers in generalized forms, such as two-digit and three-digit numbers represented as 10a + b. Students learn tests of divisibility for numbers like 2, 3, 5, 9, and 11, which help in solving complex arithmetic problems quickly without actual division. This chapter builds strong foundational skills in logical reasoning, algebraic thinking, and number theory, which are crucial for scoring high in the board exams.
Start Learning FreeKey Concepts
Generalized Form of Numbers
Expressing a two-digit number like ab as 10a + b and a three-digit number like abc as 100a + 10b + c, where a, b, and c are digits.
Divisibility by 2, 5, and 10
A number is divisible by 2 if its last digit is even, by 5 if it ends in 0 or 5, and by 10 if it ends in 0.
Divisibility by 3 and 9
A number is divisible by 3 or 9 if the sum of its digits is a multiple of 3 or 9, respectively.
Divisibility by 11
A number is divisible by 11 if the difference between the sum of digits at odd places and even places is 0 or a multiple of 11.
Puzzles with Digits
Solving cryptarithmetic puzzles where letters represent unknown digits in arithmetic operations using logical deductions.
Important Formulas
Board Exam Info
In the Bihar Board Class 7 Mathematics examination, 'Number Play' typically carries around 4 to 6 marks. Common question types include short-answer questions on divisibility tests, finding unknown digits in addition or multiplication puzzles, and problems based on the generalized forms of two-digit and three-digit numbers.
Frequently Asked Questions
What is the difference between a normal number and a generalized form?
A normal number is written with its face values (like 45), while the generalized form breaks it down according to place value, such as 45 = 10(4) + 5.
How can I easily remember the divisibility rule for 11?
Add the digits in the odd positions from the right and the digits in the even positions separately. If their difference is 0 or divisible by 11, the whole number is divisible by 11.
Why do we study number puzzles in Class 7 Maths?
Number puzzles help improve logical thinking, mental math speed, and prepare you for algebra by teaching you to find unknown values using rules.
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