what are your ideas? Post them
Do you know what divisible even means. Divisible means dividable. Try to divide all those numbers by 9. a)81 = 81/9 = 9 b)162 = 162/9 = 18 c)199 = 199/0 = 22.11111.. d)1125 = 1125/9 = 125 From this you can see that the only number which is not divisible by 9 is 199.
What do you think? First of all go on to Google and look up prime numbers. You'll get a way better understanding of them in a small amount of time. I'll give you one hint: 51 is a prime number because 3 and 17 are it's factors.
I'll give you advice, don't waste your time by posting "easy" questions onto this site. I could do that in less then a second, no joke. If need the answer then just use your calculator for it. Show us your work. Punch that in a calculator and tell us what you...