CBSE Class 5 Mathematics Be My Multiple Worksheet Set 03

Competency : Understanding Basic Concepts

Question 1. Shade out 1
Answer: Number 1 is shaded out since it is neither prime nor composite.
In simple words: The number 1 is removed from the list because it has only one factor.

Exam Tip: Remember that 1 is a unique number and is never considered a prime number.

Question 2. Shade all even numbers higher than two.
Answer: All multiples of 2 greater than 2 (such as 4, 6, 8, 10, 12, etc.) are shaded out.
In simple words: All even numbers except 2 are shaded out because they are divisible by 2.

Exam Tip: 2 is the only even prime number; all other even numbers are composite numbers.

Question 3. Shade out multiples of 5, except 5 itself
Answer: Multiples of 5 greater than 5 (such as 10, 15, 20, 25, 30, etc.) are shaded out while 5 is left unshaded.
In simple words: Keep 5 unshaded and cross out all other numbers ending in 0 or 5.

Exam Tip: Numbers that are multiples of 5 always end in either 0 or 5.

Question 4. Shade out multiples of 7, except 7 itself
Answer: Multiples of 7 greater than 7 (such as 14, 21, 28, 35, 42, 49, etc.) are shaded out while 7 is left unshaded.
In simple words: Keep 7 unshaded and cross out its other multiples in the grid.

Exam Tip: This procedure is part of the Sieve of Eratosthenes used to find prime numbers.

Question 5. The numbers which are left at the end are Prime Numbers. They are.
Answer: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97
In simple words: The numbers that remain unshaded after removing 1, all even numbers greater than 2, and all multiples of 3, 5, and 7 are prime numbers.

Exam Tip: Memorize the first few prime numbers up to 50 as they frequently appear in math problems.