The crisp new dollar bill that I have just taken from my wallet bears the serial number 24598176. It’s easy to tell that the number is exactly divisible by 2 but not by 5. Is it divisible by 3? by 4?

‘1234 is a multiple of 4’ is false. You can work out the answer by long division, if that still dwells somewhere in the deep recesses of your memory. Or by using a pocket calculator if you don’t mind ...

Examples: (1) 475 is divisible by 25 but not by 125. (2) 465 is divisible by 5 but not by a higher power of 5. As 4 + 6 + 5 = 15, it is divisible by 3 though. (3) To check for divisibility of ...

Prime numbers, vital in mathematics and competitive exams, can be quickly identified using a systematic approach. This method involves checking divisibility by primes up to the square root of the ...

The Mathematics Teacher (MT), an official journal of the National Council of Teachers of Mathematics, is devoted to improving mathematics instruction from grade 8-14 and supporting teacher education ...