What is the smallest number with exactly 14 divisors?
Many numbers can be expressed as the sum of two or more consecutive integers. For example, 15=7+8 and 10=1+2+3+4. Can you say which numbers can be expressed in this way?
Helen made the conjecture that "every multiple of six has more factors than the two numbers either side of it". Is this conjecture true?
What part of the powers of 3 and 7 tell you that it is divisible by 10?