math
posted by chris .
What are the divisibility short cuts that help you out?
Odd numbers can only be divided evenly by another odd number.
Even numbers can be evenly divided by either odd or even numbers.
2Numbers that end in 0, 2, 4, 6, or 8 are evenly divisible by 2.
3If the sum of a number's digits is evenly divisible by 3, the number is divisible by 3.
4If the last two digits are both zero or they form a two digit number evenly divisible by 4, then
the whole number is evenly divisible by 4.
5Any number ending in 5 or 0 is evenly divisible by 5.
6If the number is evenly divisible by 2 and 3, it is divisible by 6.
If the number is even and the sum of the digits is evenly divisible by 3, the whole number is
divisible by 3.
7Double the last digit and subtract from the number without the last digit. If the result is evenly
divisible by 7, so is the original number.
Multiply the lefthand digit by 3 and add the next digit. With the result, repeat as often as
necessary with the subsequent digits. If the final answer is divisible by 7, so is the original
number.
Divide the number into groups of 3 digits or thousands. Subtract the first group from the
second group. Subtract the third group from the result of the first subtraction. Continue
subtracting until the last group is subtracted. If the resulting number is divisible by 7, so is the
original number. This method works for 11 and 13 as well.
8If the last 3 digits are zero or if they form a number that is evenly divisible by 8, then the whole
number is evenly divisible by 8.
9If the sum of the digits is evenly divisible by 9, the number is evenly divisible by 9.
10Any number that ends in 0 is evenly divisible by 10.
11If all the digits in the number are the same and it has an even number of digits, the number is evenly
divisible by 11. An alternate method is to 1) add up the odd position digits, 2) add up the even position digits, and 3) calculate the difference between the two sums. If the difference is divisible by 11, the original number is divisible by 11.
Divide the number into groups of 3 digits or thousands. Subtract the first group from the
second group. Subtract the third group from the result of the first subtraction. Continue
subtracting until the last group is subtracted. If the resulting number is divisible by 11, so is the
original number.
12If a number can be evenly divided by 3 and 4, then it can be evenly divided by 12.
13Divide the number into groups of 3 digits or thousands. Subtract the first group from the
second group. Subtract the third group from the result of the first subtraction. Continue
subtracting until the last group is subtracted. If the resulting number is divisible by 13, so is the
original number.
15If a number can be evenly divided by 3 and 5, then it can be evenly divided by 15.
17Remove the last digit and multiply it by 5. Subtract the result from the rest of the number. Continue this process until you have a number smaller than 40. If this final result is divisible by 17, then the original number is divisible by 17.
18If the number is evenly divisible by either 2 and 9 or 3 and 6, the number is divisible by 18.
Respond to this Question
Similar Questions

Mathematics  Cardinal Number
Hi, This is a really easy question. I think I am analyzing it too much: Find the cardinal number of the following set: {1,3,5,.....1001} Thanks in advance. Ok, the cardinal number is the numbe of members of a set. The set you've given … 
math problem
My ID number is quite remarkable.Its a 9 digit number with the digits 19 appearing only once. The entire 9 digit nuymber is divisible by 9. If you remove the last digit, the remaining 8 digit number is divisible by 8. If you remove … 
Geometry
Working on conjectures. The question is Conjecure: The product of any two odd numbers is _____? 
Reposted math question
"what do you call numbers that cannot be arranged into 2row arrays? 
SUMS?
what is the sum of the first towo odd numbers? 
math
Consider the following sums of numbers and how they are formed: 1 odd number } 2 odd numbers 678 3 odd numbers 64748 Predict the following sum and complete the generalization: a. 1 + 3 + 5 + 7 + 9 + 11 = ? 
Statistics
a roulette wheel has 40 slots evenly divided between red (even) and green (odd) slots totaling 38 and a "0" and a "00". what is the probability of the ball landing in an: A)even number < 10 B) other than an even or odd number C) … 
Math
1. What is the 117th odd natural number? 2. What is the greatest threedigit number divisible by 3, 4, 5, and 6? 
Math! Please check!
Consider the statement: If two whole numbers are even, then their sum is odd. What assumption should be made to prove the statement indirectly? 
math
in lotto draw balls 150 mixed together. machine randomly selects numbers 13,11,7,27,41. is the 6th number drown A. more like to be odd than even b. more likely to be even than odd c. equally likely i could not decide, as long as there …