ON THE MOTORWAY

On a car journey, get the children to find the digit sum of car number plates.

Any number of any size can always be reduced to a single figure by adding its digits.

- For example 42 has two digits which add up to 6.

We say "the digit sum of 42 is**6**". - The digit sum of 413 is
**8**because 4+1+3=8. - For 20511 the digit sum is
**9**.

Question Comment !

Tutorial Title | |

Question Title | |

No Questions | 0 |

Questions Asked | 0 |

Skipped Questions | 0 |

Correctly Answered | 0 |

Wrongly Answered | 0 |

Total Question Attempts | 0 |

Current Question Attempts | 0 |

Skip Question

Reset Test

Halt Test

No Questions | 0 |

Questions Asked | 0 |

Skipped Questions | 0 |

Correctly Answered | 0 |

Wrongly Answered | 0 |

Total Question Attempts | 0 |

Time Taken

Close

On The Motorway (1)

- Now suppose we want the digit sum of 417.

Adding 4, 1 and 7 gives 12.

But as 12 is a 2-figure number we add its digits to

get 3 (1+2=3).

We could write**417 = 12 = 3**.

- And so 737 = 17 = 8.

We simply add the digits in the number and add again if necessary.

This is simple and one of its uses is in checking sums, as we will see.

On The Motorway (2)

All things that can be

known have number;

for it is not possible

that without numbers

anything can be either

conceived or known

known have number;

for it is not possible

that without numbers

anything can be either

conceived or known

PHILOLAUS