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Reach 100

Stage: 2 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Here is a grid of four "boxes":

Square divided into four.

You must choose four different digits from $1 - 9$ and put one in each box. For example:

Square divide into four, with 5,2,1 & 9 in the sections.

This gives four two-digit numbers:

$52$ (reading along the $1$st row)
$19$ (reading along the $2$nd row)
$51$ (reading down the left hand column)
$29$ (reading down the right hand column)

In this case their sum is $151$.

Your challenge is to find four different digits that give four two-digit numbers which add to a total of $100$.

How many ways can you find of doing it?

This problem is adapted from Make 200 from 'Mathematical Challenges for Able Pupils Key Stages 1 and 2', published by DfES. You can find out more about this book, including how to order it, on the Standards website here .


The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice. More information on many of our other activities can be found here.
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