Counting and Whole Numbers
What You’ll Learn
Section titled “What You’ll Learn”In this lesson you’ll practice counting whole numbers forward and backward and get comfortable reading and writing numbers from 0 to 100.
The Concept
Section titled “The Concept”Whole numbers are the counting numbers: 0, 1, 2, 3, 4… (no fractions or negatives here).
Counting forward (adding 1 each time): 0 → 1 → 2 → 3 → … Counting backward (subtracting 1 each time): 10 → 9 → 8 → 7 → …
Skip-counting (counting by 2s, 5s, 10s) helps see patterns:
- By 2s: 0, 2, 4, 6, 8, 10…
- By 5s: 0, 5, 10, 15, 20…
- By 10s: 0, 10, 20, 30…
Here’s what skip-counting by 5s looks like on a number line, where each jump moves 5 spaces forward:
And skip-counting by 10s, bigger jumps, same idea:
Reading numbers:
- 23 = twenty-three
- 45 = forty-five
- 100 = one hundred
Writing numbers: Say it, then write it. “sixty-seven” = 67.
Worked Example
Section titled “Worked Example”Count forward by 5s to 50: 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50.
Count backward from 30 by 3s: 30, 27, 24, 21, 18, 15, 12, 9, 6, 3, 0.
On a number line, counting backward means jumping left. Here’s the first step from 30 back to 27:
Read and write: “eighty-nine” = 89 “forty-two” = 42
Real-World Application
Section titled “Real-World Application”Counting is used constantly:
- Pages in a book or report (page 1 to page 100)
- Money: counting coins or bills (quarters = 25 cents each)
- Time: counting hours worked or minutes left
- Shopping: counting items in your cart or people in line
Skip-counting helps with patterns: money by 5s (nickels), 10s (dimes), or 100s (dollars).