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?
Do you know a quick way to check if a number is a multiple of two? How about three, four or six?
Although we had lots of answers to this problem, very few of you explained your solutions carefully. Alistair from Histon and Impington Infant School sent us this solution:
Chris, Isobel, Wui Shen and Alex from Maadi British International School in Cairo noticed something else:
We thought about the problem and worked it out together first. When we had our answer we tried to work out how to get our first numbers.
Wui Shen said we could take 1 away from the tens column and + 1 to the units column.
Isobel said we could + the two numbers and find two numbers that equal the same number.
Jordan from London explained why Wui Shen's method works: