## Subtracting Larger Whole Numbers

#### Introduction

Subtraction means reducing the value of one number by another to find the new value. For example, if you have 7 apples, and give away 3, you are left with 4 (7-3=4). Subtraction is one of the first things you learn in math.

Working with very large numbers isn't much different from working with small numbers; you follow the same processes, just more times.

#### Terms

## Lesson

To subtract numbers from one another, you do it column by column. The same is true of large numbers.

Let's take the sum:

489,563 - 38,741 = ?

The first thing to do is to write them on top of one another, making sure we line up the digits:

4 | 8 | 9 | 5 | 6 | 3 |
---|---|---|---|---|---|

- | 3 | 8 | 7 | 4 | 1 |

Then we start from the furthest right and subtract the bottom digit from the top.

Since 3 - 1 = 2, we can put that in the answer row:

4 | 8 | 9 | 5 | 6 | 3 |
---|---|---|---|---|---|

- | 3 | 8 | 7 | 4 | 1 |

2 |

We then move on to the tens column. Since 6-4 = 2, we can add that to the answer row:

4 | 8 | 9 | 5 | 6 | 3 |
---|---|---|---|---|---|

- | 3 | 8 | 7 | 4 | 1 |

2 | 2 |

Then we come to the hundreds column. This presents us with a bit of a problem since 5-7 is a negative number. Therefore, we need to 'borrow' from the column one to the left. To do that, we take the 9 that's in the thousands column, strike through it and change it to 8 (because we are 'borrowing' 1). Then, with the borrowed 1, we put in front of our 5 to make 15.

4 | 8 | 15 | 6 | 3 | |
---|---|---|---|---|---|

- | 3 | 8 | 7 | 4 | 1 |

2 | 2 |

We can now do the sum of 15 - 7 in the hundreds column, which gives us 8.

4 | 8 | 15 | 6 | 3 | |
---|---|---|---|---|---|

- | 3 | 8 | 7 | 4 | 1 |

8 | 2 | 2 |

In the thousands column, our new value at the top is 8, so we do 8-8, which gives us 0 for the answer row:

4 | 8 | 15 | 6 | 3 | |
---|---|---|---|---|---|

- | 3 | 8 | 7 | 4 | 1 |

0 | 8 | 2 | 2 |

Next, we move to the ten-thousands column, and do 8-3, and add the 5 to the answer row.

4 | 8 | 15 | 6 | 3 | |
---|---|---|---|---|---|

- | 3 | 8 | 7 | 4 | 1 |

5 | 0 | 8 | 2 | 2 |

In the final column (hundred-thousands) we only have the 4, and nothing to subtract from it, so we can put it unchanged in the answer row.

4 | 8 | 15 | 6 | 3 | |
---|---|---|---|---|---|

- | 3 | 8 | 7 | 4 | 1 |

4 | 5 | 0 | 8 | 2 | 2 |

Therefore, the answer is:

489,563 - 38,741 = 450,822

If you need to work with even larger numbers, the process is exactly the same.