  Math Central - mathcentral.uregina.ca  Quandaries & Queries    Q & Q    Topic: divisibility by 3   start over

7 items are filed under this topic.    Page1/1            Divisibility by 3 2018-11-20 From Ray:There is a rule that a number is divisible by 3 if the sum of its digits are divisible by 3 (for example, 81=8+1=9 {divisible by 3} and 33=3+3=6 {again, divisible by 3}) I know this works but I don't know why! Please help.Answered by Penny Nom.     Some 6 digit numbers 2012-10-23 From Mason:How many different 6 digit numbers can you make using the digits 1 ,2 5, 6, 7, and 9? How many of these six-digit numbers are divisible by 6?Answered by Penny Nom.     Powers 2010-10-20 From dylan:how do you write 20736 in exponential form .same for 1728 and 50625. is there a formula to figure out how to express large know numbers in exponential form.Answered by Penny Nom.     Divisibility by 3 2010-05-23 From Cathleen:To math central. I have to do a maths extension question that I don't understand. At first I thought I did. It is about the dividing by three. In one part of the question, it asks me to show that the rule of division by three does not work for 23142 with a little 5 down the bottom. What doe base 5 mean? We first thought that the little 5 down the bottom meant multiplying y the power of five. Can you please tell me what it means so I can finish this question?Answered by Penny Nom.     The sum of the digits of a number 2008-06-23 From Ben:Question: Using mathematical induction, prove that if the sum of the digits of a number is divisible by three, then the number itself is also divisible by 3.Answered by Penny Nom.     Divisibility rules 2001-09-07 From A student:Why is it that when you add the digits of a number you can tell what the multiples of that number are. Example: 12131313111, 1+2+1+2+1+3+1+1+1=18, therefore 12131313111 is divisble by 2, 9, 18, & 3 because those numbers are divisble by 18. Answered by Penny Nom.     Divisibility by 3 2000-03-24 From Pat Walsh:W hy does it work when you add the digits of a number then divid by three to see if the number is divisible by threeAnswered by Penny Nom.      Page1/1    Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.    about math central :: site map :: links :: notre site français