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Gran, How Old Are You?

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

Mum and her four children live with Gran at 13 Drywater Street.

One day, Charlie, who is the third child, asked, "Gran, how old are you?"

Gran answered, "My Grandmother would have said 'As old as my tongue and a little older than my teeth!' but I will tell you how to work out my age."

"If you multiply Mum's age with your age and with the ages of your brother and sisters you will get the answer $111 111$.

If you add Mum's age along with the ages of all you four children the total will be my age."

Charlie worked this out very quickly, because he knew his Mum's age, his age and the ages of his brother and sisters.

"Oh Gran!" he called as he ran off to play outside, "You are old!"

pic

How old was his Gran?
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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