Divisibility by 4 Test:
This one works great - about half of the time.
A number is divisible by 4 if the last two digits
Let me make that clearer:
Look at the last two digits of a number...
So the whole thing is divisible by 4.
What about this guy?
Hmm... I don't know that one off the top of my head... because it's not an answer from our times tables!
These I know:
Anything past that I'd either have to check with a calculator or long division... But, I could do THAT for 572 too! If it was a really big number, like 7,283,472, just checking the last two numbers would save a lot of time, though.
So, this test is great for numbers that end in 48 or less and for really big numbers.