Solution: Prime Numbers from 1 to 100
We are asked to
identify and tick all the prime numbers from 1 to 100.
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✔ What are Prime Numbers?
A
prime number is a natural number greater than 1 that has
no positive divisors other than 1 and itself.
In other words, it can only be divided evenly by 1 and the number itself.
> 🔹
Note: The number
1 is not a prime number because it has only one divisor (itself), and the definition requires two distinct divisors.
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✔ List of Prime Numbers from 1 to 100
Let’s go through the grid and identify all prime numbers:
| Row | Prime Numbers |
|-----|----------------|
| 1–10 |
2, 3, 5, 7 |
| 11–20 |
11, 13, 17, 19 |
| 21–30 |
23, 29 |
| 31–40 |
31, 37 |
| 41–50 |
41, 43, 47 |
| 51–60 |
53, 59 |
| 61–70 |
61, 67 |
| 71–80 |
71, 73, 79 |
| 81–90 |
83, 89 |
| 91–100 |
97 |
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✔ Final List of Prime Numbers (1–100):
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
✔ There are
25 prime numbers between 1 and 100.
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📌 How to Identify Them?
You can use the
Sieve of Eratosthenes method:
1. Start with 2 — it's prime.
2. Eliminate all multiples of 2 (except 2 itself).
3. Next unmarked number is 3 — prime; eliminate its multiples.
4. Continue with 5, 7, etc., up to √100 = 10.
This helps efficiently filter out composites.
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✘ Non-Primes (Examples):
-
Even numbers > 2 → divisible by 2 → not prime
-
Multiples of 3, 5, 7, etc., are composite unless they're the number itself
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✔ Answer to "What are prime numbers?"
>
Prime numbers are natural numbers greater than 1 that have exactly two distinct positive divisors: 1 and the number itself.
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✔ Final Step: Tick the Primes in the Grid
You should
tick the following numbers in the table:
```
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
```
All others are
composite or
1 (neither prime nor composite).
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Let me know if you'd like a printable version with ticks!
Parent Tip: Review the logic above to help your child master the concept of prime number worksheet.
