Class 7 Maths - MP
Number Play
The chapter 'Number Play' in Class 7 Mathematics introduces students to the fascinating world of numbers through puzzles, riddles, and mathematical patterns. It focuses on writing numbers in generalized form using digits and variables like 10a + b, and explores tests of divisibility for numbers such as 2, 3, 5, 9, and 11. For MP Board students, this chapter is crucial as it builds logical reasoning and problem-solving skills, frequently appearing in exams through puzzles, number replacement riddles, and short-answer questions based on divisibility rules.
Start Learning FreeKey Concepts
Generalized Form of Numbers
A two-digit number like ab can be written in its expanded or generalized 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 2, 5, and 10
A number is divisible by 2 if its last digit is even (0, 2, 4, 6, 8), by 5 if the last digit is 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 all 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 its digits at odd places and even places is either 0 or a multiple of 11.
Important Formulas
Board Exam Info
In the MP Board Class 7 Mathematics examinations, this chapter generally carries around 4 to 6 marks. Common question types include finding unknown alphabets in addition/multiplication puzzles, applying divisibility tests to check if a large number is divisible by 3, 9, or 11, and solving word problems based on number reversals.
Frequently Asked Questions
Why do we write numbers in generalized form as 10a + b?
We write numbers in generalized form to represent them algebraically using their place values, which helps us solve puzzles and prove divisibility rules easily.
How can I quickly check if a large number is divisible by 11?
Add the digits at odd positions from the right, add the digits at even positions, and find their difference. If the result is 0 or divisible by 11, the number is divisible by 11.
Are number puzzles difficult to solve in the MP Board exam?
No, number puzzles are usually simple if you test values from 0 to 9 step-by-step using basic addition and multiplication rules.
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