HOW WE WORKED IT OUT: The units on the first two numbers have to
add up to 10 to make this work and the second pair of numbers on
the right hand side also have to add up to 10. The tens in the
first product on the right hand side have to be 10 apart.
Suzanne Abbott and Nisha Doshi, (Y10) The Mount School, York proved
that the method always works. Here is their solution:
Yes these are all correct. Here are some more examples
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.