Brain teasers
Share
Brain teasers
https://www.tes.com/magazine/archive/brain-teasers-1
Maths challenge
Age 7-9
Ben’s numbers
Ben has written a list of different numbers.
The digits of each number add up to 5.
None of the digits is zero.
Here is one of them: 23
Ben has written all the numbers he can think of.
How many different numbers are there in his list?
Maths challenge
Age 9-11
Make five numbers
You need a set of ten cards numbered 0 to 9
Use every card once in each of the following problems.
Arrange them to make:
a. five numbers that are multiples of 3;
b. five numbers that are multiples of 7;
c. five prime numbers.
BRAIN TEASER SOLUTIONS
Ben’s numbers:
There are 16 different numbers in Ben’s list:
5, 14, 23, 32, 41, 113, 122, 131, 212, 221, 311, 1112, 1121, 1211, 2111, 11111.
Make five numbers:
For example:
a. 12, 39, 45, 60, 78 b. 7, 42, 63, 98, 105 c. 5, 23, 67, 89, 401 There are other solutions.
You've reached your limit of free articles this month. Subscribe for £1 per month for three months and get: