Question

Find out the divisibility rule of prime number from 1 to 20.​

Answer 1

Answer:

19-3-2011 19-3-2011 and the other one square 1️⃣ 26914

Answer 2

• 1 - no specific rule . any integer is divisible by 1.
• 2 - all even numbers are divisible by 2 .
• 3 - Sum the digits. The result must be divisible by 3.
• 4 - The last two digits form a number that is divisible by 4.
• 5 - The last digit is 0 or 5.
• 6 - It is divisible by 2 and by 3.
• 7 - Adding the last two digits to twice the rest gives a multiple of 7.
• 8 - Add the last digit to twice the rest. The result must be divisible by 8. The last three digits are divisible by 8.
• 9 - Sum the digits. The result must be divisible by 9.
• 10 - The ones digit is 0.
• 11 - Add the last digit to the hundreds place (add 10 times the last digit to the rest). The result must be divisible by 11.
• 12 - Subtract the last digit from twice the rest. The result must be divisible by 12.
• 13 - Add 4 times the last digit to the rest. The result must be divisible by 13.
• 14 - Add the last two digits to twice the rest. The result must be divisible by 14.
• 15 - It is divisible by 3 and by 5.
• 16 - The last four digits must be divisible by 16.
• 17 - Add 9 times the last digit to 5 times the rest. Drop trailing zeroes.
• 18 - It is divisible by 2 and by 9.
• 19 - Add 4 times the last two digits to the rest.
• 20 - The number formed by the last two digits is divisible by 20. It is divisible by 4 and 5.