**Numbers**

**Counting Numbers**

We use numbers to count anything. The numbers starting from 1 to 100 and
beyond 100, are used for counting. These are called
**counting numbers**.

There are mainly two ways of counting-

**Counting Forward****Counting Backward**

**Counting Forward:**

In counting forward, we count on by 1. Each number is one more than the previous number.

**Example:**

The frog is jumping on the numbers in forward direction. Each jump is one more than the previous jump.

- Forward counting is useful in finding numbers that come after.
- In forward counting, a bigger number always comes after a smaller number.

**Example:**

Here, we need to find out the number that comes after:

a. 17 b. 49

After counting forward the given numbers, we get:

**Skip Counting:**

To count many things quickly, we count forward by the numbers other than 1. In this method, we keep adding the same number each time to the previous number.

**Count forward by 2â€™s:**

In this method, we count forward in 2. We count forward by skipping one number in between the previous and the next number.

**Example:**

27 | 29 | ? | ? | ? |

Here, we need to count the numbers in forward direction by skipping one number in between like the following:

So, the correct answer is:

27 | 29 | 31 | 33 | 35 |

**Count forward by 5â€™s:**

In this method, we count forward by 5. We count forward by skipping four numbers in between the previous and the next number.

**Example:**

5 | 10 | 15 | ? | ? | ? |

Count the five numbers from 5. We get the number 10. Again, count the five numbers from 10. We get the number 15.

So, the correct answer is:

5 | 10 | 15 | 20 | 25 | 30 |

- In the same fashion we can count forward in 3â€™s, 4â€™s, 6â€™s, 10â€™s, etc.

**Counting Backward:**

In counting backward, we count down by 1. Each number is one less than the previous number. number decreases in backward counting.

- Backward counting is useful in finding numbers that come before.
- In backward counting, a smaller number always comes after a bigger number.

**Example 1:**

Here, we need to find the number that comes before:

a. 76 b. 63

After counting numbers backward, we get:

Sometimes we use backward counting to get the answers for the numbers, that are increasing.

**Example 2:**

? | ? | ? | 85 | 87 |

Here, we need to count the numbers backward by skipping one number in between like the following:

So, the correct answer is:

79 | 81 | 83 | 85 | 87 |

**Count backward by 2â€™s:**

In this method, we count backward in 2. We count backward by skipping one number in between the previous and the next number.

**Example:**

18 | 16 | 14 | ? | ? | ? |

Here, we need to count the numbers in backward direction by skipping one number in between like the following:

So, the correct answer is:

18 | 16 | 14 | 12 | 10 | 8 |

**Count backward by 5â€™s:**

In this method, we count backward in 5. We count in backward direction by skipping three numbers in between the previous and the next number.

30 | 25 | 20 | ? | ? | ? |

Here, we need to count the numbers in backward direction by skipping four numbers in between like the following:

So, the correct answer is:

30 | 25 | 20 | 15 | 10 | 5 |

- In the same fashion we can count backward in 3â€™s, 4â€™s, 6â€™s, 10â€™s, etc.

**Did you know?**

The word "hundred" is derived from the Old Norse word

"hundrath," which means 120, not 100.

**Fun fact:**

Forty is the only number name in English whose letters appear in correct alphabetical order.