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For younger learners

Early years foundation stage

American Billions Poster

Age

11 to 14

Challenge level

Exploring and noticing Working systematically Conjecturing and generalising Visualising and representing Reasoning, convincing and proving

Being curious Being resourceful Being resilient Being collaborative

Problem

This poster is based on the problem American Billions.

The poster is available as a PDF, or the image below can be clicked on to enlarge it.

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Student Solutions

Answer: 3816547290

Why?

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First try 258:

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The remaining possibilities are 1472589630 and 7412589630, but neither of 1472589 and 7412589 are divisible by 7

Next try 654:

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The remaining possibilities are 1836547290, 1896543270, 1896547230, 7896543210, 3816547290, 9816543270 and 9816547230

Out of 1836547, 1896543, 1896547, 7896543, 3816547, 9816543 and 9816547, only 3816547 is a multiple of 7.

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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.

NRICH is part of the family of activities in the Millennium Mathematics Project.