Determine Divisibility

DETERMINE DIVISIBILITY

We now take up the interesting question as how one can we determine  whether a certain given number , si divisible by a certain given divisor. For different divisors, the rules differ at large. Let us discuss the rule for some divisors.

DETERMINE THE DIVISIBILITY BY 2

Rule : Any number, the last digit of which is either even or o, is divisible by 2

example: 12,86,130.

DETERMINE THE DIVISIBILITY BY 3

Rule : If the sum of the digits of a number is divisible by 3, the number is also divisible by 3

Example :  123 =  1 + 2 + 3  = 6 divisible by 3; hence 123 is also divisible by 3.

DETERMINE THE DIVISIBILITY BY 4

Rule : If the last two digits of a number is divisible by 4, the number is divisible by 4. The number having two or more zeros at the end is also divisible by 4

Example : 1) 526428 : 28 is divisible by 4 , therefore , the number is divisible by 4

2) 5300 : There are two zeros at the end, so it is divisible by 4.

Note:  The same rule is applicable to check the divisibility by 25. That is , a number divisible by 25 if its last two digits are either zeros or divisible by 25.



DIVISIBILITY RULES OF SOME MORE NUMBERS



DIVISIBILITY BY 5

Rule : If a number ends with 5 or 0, then divisible by 5

example:  1) 1345

DIVISIBILITY BY 6

Rule : If a number is divisible by both 3 and 2 , the number is also divisible by 6. So, for a number to be divisible by 6.

1) The number should end with an even digit or 0 and

2) The sum of its digits should be divisible by 3.