Counting backwards

In this lesson, we will learn:

• How do we count backwards using: the numbers 9 to 0, number lines (and negative numbers), and big numbers (up to millions)?
• Counting Backwards can help us write subtraction statements.

Notes:

• We use numbers to represent how many things there are.
• You can do the exact opposite of normal counting by counting BACKWARDS:
• 10, 9, 8, 7, 6, 5, 4, 3, 2, 1…


• Counting backwards means the counting numbers are getting SMALLER
• If you look at a number line, counting forwards means going from right to left

• Negative numbers also count backward by going from right to left on a number line
• Don’t get confused! The negative numbers (digits) are going forwards, but they have a negative sign!
• The bigger your negative, the smaller your value (more negative = smaller)
• Ex. counting backwards in negatives: -1, -2, -3, -4, -5, …


• Recall: number PLACE VALUES!

• The smaller place values are on the right, the bigger place values are on the left
• When the digit decreases (from 9 to 0): after you hit 0, next you will decrease 1 FROM the place value on the left. Your digit will then start again from 9 (and count down to 0, repeating the process)

• You can also use your fingers to count backward and find out how many numbers you have decreased (counted down) by.
• Put down all your fingers (zero fingers up) when you start on your first number.
• Each number you count down, raise one more finger.
• When you reach your last number, you can count your raised fingers
• Ex. counting from 32 down to 27: you count down by five

• This can allow you to make subtraction statements!
• [starting #] – [how much you counted down] = [last #]
• Ex. counting from 32 down to 27, the subtraction statement is: 32 – 5 = 27