SOLUTION: Test each of these numbers for divisibility by 3, 5, and 11 without using a calculator: Explain your reasoning. a. 56743 b. 69916800

Algebra ->  Divisibility and Prime Numbers  -> Lessons -> SOLUTION: Test each of these numbers for divisibility by 3, 5, and 11 without using a calculator: Explain your reasoning. a. 56743 b. 69916800       Log On


   

Question 376473: Test each of these numbers for divisibility by 3, 5, and 11 without using a calculator:
Explain your reasoning.
a. 56743
b. 69916800

Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
a) Digits add to 5%2B6%2B7%2B4%2B3=25 which is not divisible by 3, so the number is not divisible by 3.
Doesn't end in 0 or 5 so no chance with 5.
Also not divisible by 11.
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.
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b) Digits add to 6%2B9%2B9%2B1%2B6%2B8=39 which is divisible by 3, so the number is divisble by 3.
Ends in 0 so it's divisible by 5.
Not divisible by 11.