



 
Hi Cathleen, Using our standard base 10 notation the number 5437 is five thousand, four hundred and thirty seven, or said using digits 5000 + 400 + 30 + 7. Using powers of 10 this is
Numbers can be expressed in bases other than 10, that is using powers of the base. For example 3402_{5} is the number
I might write this 477_{10} but usually when we express numbers using the base 10 notation we don't use the subscript of 10. The point in your maths extension question is that the test for divisibility by 3 is not valid if you express the number in base 5 notation. For example the sum of the digits of 3402_{5} is 3 + 4 + 0 + 2 = 14 which is not divisible by 3 and yet 3402_{5} = 477 and 477 is divisible by 3. The number in your pr0blem is 23142_{5} and the sum of its digits is divisible by 3. Express 23142_{5} is base 10 notation and test to see if it is divisible by 3. I hope this helps,  


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