Grade:5 Mathematics Activity. 23 61 32 21 82 42 18 34 16 50 75 39 35 40 69 25 By Using the grid, Answer all the questions: 1. Write all pairs of numbers whose sum is 100. 2. Write all pairs of numbers whose difference is 18. 3. Write all numbers which round off to 100. 4. Write the Roman Numeral for 25, 61 and 39.
Answers
Step-by-step explanation:
A prime number is a whole number greater than 1 that can only be divided by itself and 1. The smallest prime numbers are 2, 3, 5, 7, 11, 13, 17, 19 and 23. The number 2 is the only even prime number.
Example:
7=1×7 The number 7 has only two factors: 1 and itself.
11=1×11 The number 11 has only two factors: 1 and itself.
Composite numbers: A composite number has more than two factors. Composite numbers can be broken down into prime factors.
Example:
6 = 2×3 2 and 3 are prime numbers.
20 = 2×2×5 2 and 5 are prime numbers.
35 = 5×7 5 and 7 are prime numbers.
Prime factors: Find the prime factors of 30.
30 = 2×3×5
The prime factors of 30 are the numbers 2, 3, and 5.
Begin with the lowest prime number that is a factor of 30. Divide by 2 to get the factor 15.
Now use the lowest prime number that is a factor of 15. Divide by 3 to get the factor 5 which is also a prime number.
You can also find the prime factors of a whole number by drawing a factor tree.
30 = 2×3×5
Divisibility of numbers:
You can use the Sieve of Eratosthenes to find prime numbers.
Answer:
Step-by-step explanation:
69+21=100
75+25=100
82+18=100
61+39=100