Table of Contents
Who invented the rules of divisibility?
Although there are divisibility tests for numbers in any radix, or base, and they are all different, this article presents rules and examples only for decimal, or base 10, numbers. Martin Gardner explained and popularized these rules in his September 1962 “Mathematical Games” column in Scientific American.
What are the basic rules of divisibility?
The Divisibility Rules
- Any integer (not a fraction) is divisible by 1.
- The last digit is even (0,2,4,6,8)
- The sum of the digits is divisible by 3.
- The last 2 digits are divisible by 4.
- The last digit is 0 or 5.
- Is even and is divisible by 3 (it passes both the 2 rule and 3 rule above)
What is 7’s divisibility rule?
The divisibility rule of 7 states that, if a number is divisible by 7, then “the difference between twice the unit digit of the given number and the remaining part of the given number should be a multiple of 7 or it should be equal to 0”. For example, 798 is divisible by 7.
Who discovered divisibility rule of 7?
Chika Ofili
About Chika’s discovery A 12-year old Nigerian boy, Chika Ofili, made history this year after his new discovery in the field of mathematics. He was awarded at the TruLittle Hero Awards for discovering the new divisibility test of 7, popularly called as Chika’s Test. Chika displaying his award with his family.
Why divisibility rules are important?
Divisibility rules of whole numbers are very useful because they help us to quickly determine if a number can be divided by 2, 3, 4, 5, 9, and 10 without doing long division. This is especially useful when the numbers are large.
Is 100 divisible by 4 yes or no?
We start with the smallest number possible that has zero as the last two digits, 100. If we divide 100 by 4, the quotient is 25 and the remainder is 0. 100 is divisible by 4.
What is divisibility rule 11?
Divisibility Rules for 11 If the difference of the sum of alternative digits of a number is divisible by 11, then that number is divisible by 11 completely.
What is Chika test?
In a bored moment, Chika had turned his mind to the problem and this is what he came up with. He realised that if you take the last digit of any whole number, multiply it by 5 and then add this to the remaining part of the number, you will get a new number.
Is 127 divisible by any number?
Solution: 127 is a prime number and it has only two factors, i.e. 1 and 127.
How do you know if a number is divisible by 11?
Take the alternating sum of the digits in the number, read from left to right. If that is divisible by 11, so is the original number. So, for instance, 2728 has alternating sum of digits 2 – 7 + 2 – 8 = -11. Since -11 is divisible by 11, so is 2728.
How do you check divisibility by 14?
The divisibility rule for 14 is that if the number is divisible by both 2 and 7 then the number is exactly divisible by 14. Here the last digit is, even so, the number 1428 is divisible by 2.
What is divisibility test of 10?
In order to apply the divisibility rule for 10, the digit that is last in a number has to be 0. This works whether the number is 70, 700, or 7,000. The rule also works if the numbers do not have 0 as a middle digit such as 210, 340, and 620. All of them are divisible by 10.