Grade by Grade
C. Algebra · Patterns, Variables, Coding and Modelling

Number Patterns to 100

C1.4About 40 minutes
Learning goals
  • I can find and describe patterns on a hundred chart.
  • I can skip count by 2s, 5s, 10s and 25s and describe the patterns I see.
  • I can use patterns to show how numbers are related, like 10 more and 10 less.
  • I can create my own number pattern up to 100 and describe it.

Words to know

hundred chart
A chart with the numbers 1 to 100 in 10 rows of 10.
row
A line of numbers that goes across (left to right).
column
A line of numbers that goes down (top to bottom).
skip count
To count by jumps of the same size, like 5, 10, 15, 20.
relationship
How numbers are connected, like 30 is 10 more than 20.

Remember from Grade 1

Last year you found patterns on a 50 chart. Going down a column was 10 more. Now you will use a hundred chart and explore numbers all the way to 100!

12345678910
11121314151617181920
21222324252627282930
31323334353637383940
41424344454647484950
51525354555657585960
61626364656667686970
71727374757677787980
81828384858687888990
919293949596979899100
A hundred chart. Each row has 10 numbers. Look at the ones digit going down a column and the tens digit going across a row.

Patterns going across and down

  • Across a row, each number is 1 more. 31, 32, 33, 34... The ones digit goes up by 1 and the tens digit stays the same (until the end of the row).
  • Down a column, each number is 10 more. 4, 14, 24, 34, 44... The ones digit stays the same and the tens digit goes up by 1.
  • Up a column is 10 less. Left in a row is 1 less.
3637384647485657581 more →← 1 lessup a column: 10 lessdown a column: 10 more
A piece of the hundred chart around 47. One step down is 57 (10 more), one step up is 37 (10 less), right is 48 (1 more) and left is 46 (1 less).
Worked example

Moving on the chart

Start at 47. What number is 10 more? 10 less? 1 more? 1 less?

  1. 10 more is one row down: 57. The tens digit goes from 4 to 5.
  2. 10 less is one row up: 37.
  3. 1 more is one step right: 48.
  4. 1 less is one step left: 46.

10 more: 57. 10 less: 37. 1 more: 48. 1 less: 46.

Skip counting patterns

When you skip count and colour the numbers on a hundred chart, you see beautiful patterns.

  • By 10s: 10, 20, 30, ..., 100. All the numbers are in the last column. Every ones digit is 0.
  • By 5s: 5, 10, 15, 20, ... The numbers make two columns. The ones digits go 5, 0, 5, 0. That is a repeating pattern!
  • By 2s: 2, 4, 6, 8, 10, 12... The ones digits go 2, 4, 6, 8, 0 again and again. These are the even numbers. They make 5 columns with gaps in between, like stripes.
Count byFirst numbersOnes digits repeat
2s2, 4, 6, 8, 10, 12, 142, 4, 6, 8, 0
5s5, 10, 15, 20, 25, 305, 0
10s10, 20, 30, 40, 500
25s25, 50, 75, 1005, 0
Skip counting patterns. Notice the ones digits repeat!

Counting by 25s

A quarter is worth 25¢. Count quarters by 25s: 25, 50, 75, 100. Four quarters make 100¢, which is the same as one dollar!

🪙 25 → 🪙🪙 50 → 🪙🪙🪙 75 → 🪙🪙🪙🪙 100

Patterns that show number relationships

Patterns can show how numbers are connected. Look at this list. What do you notice?

  • 3 + 7 = 10
  • 13 + 7 = 20
  • 23 + 7 = 30
  • 33 + 7 = 40

The first number goes up by 10, and the answer also goes up by 10. The 3 and the 7 always make a new ten!

Worked example

Making 100 with tens

Continue the pattern and describe it:

10 + 90 = 100

20 + 80 = 100

30 + 70 = 100

___ + ___ = 100

  1. The first number goes up by 10: 10, 20, 30, next is 40.
  2. The second number goes down by 10: 90, 80, 70, next is 60.
  3. The total stays 100. When one part gets 10 more, the other part gets 10 less.
  4. Check: 4 tens + 6 tens = 10 tens = 100.

40 + 60 = 100. One part grows by 10 while the other shrinks by 10, so the total stays the same.

Just for fun

Funny but true: counting to 100 by 1s takes 100 numbers. Counting by 25s takes only 4: 25, 50, 75, 100. Quarters are the speedy way to a dollar! 🪙

Ten full ten frames make 100. 4 frames and 6 frames make 10 frames, which is 100.
Worked example

Create your own pattern

Create a number pattern to 100 that starts at 4 and grows by 10. Describe it.

  1. Start at 4.
  2. Add 10 each time: 4, 14, 24, 34, 44, 54, 64, 74, 84, 94.
  3. The next would be 104, which is more than 100, so stop at 94.
  4. Describe it: The ones digit is always 4. The tens digit goes up by 1. On the hundred chart, it goes straight down a column.

4, 14, 24, 34, 44, 54, 64, 74, 84, 94. All the numbers end in 4.

Your turn

1

What number is 10 more than 63?

2

What number is 10 less than 81?

3

Count by 5s: 55, 60, 65, ___, ___

4

Count by 25s: 25, 50, ___, ___

5

Continue: 6, 16, 26, 36, ___

6

Continue: 5 + 5 = 10, 15 + 5 = 20, 25 + 5 = 30, ___

7

When you count by 2s, which ones digits do you see?

Hands-on activity

Colour a hundred chart

You need: a hundred chart (draw a 10 by 10 grid and write 1 to 100, or print one), and crayons.

  1. Colour every number you say when you count by 5s in yellow.
  2. Circle every number you say when you count by 10s. What do you notice? (They are all yellow too!)
  3. On a second chart, colour the count by 2s numbers. Describe the stripes.
  4. Start on any number in the first row. Hop down the column with your finger and say each number. What stays the same?
  5. Bonus: line up 4 quarters (or 4 paper circles marked 25¢). Count them by 25s.

Look at the digits

When you are not sure, look at the digits. In a count by 10s from any number, the ones digit never changes. In a count by 5s, the ones digit takes turns.

More practice: warm-up

1

Count by 10s: 30, 40, 50, ___

2

What is 1 more than 79?

3

Count by 2s: 40, 42, 44, ___

4

On a hundred chart, what number is right below 25?

5

Count back by 10s: 100, 90, 80, ___

More practice: on your own

1

Continue and describe: 98, 88, 78, 68, ___, ___

2

Continue: 2 + 8 = 10, 12 + 8 = 20, 22 + 8 = 30, ___ + 8 = ___

3

Which of these numbers will you say if you count by 5s from 5? 35, 42, 60, 87, 95

4

Continue: 50 + 50 = 100, 60 + 40 = 100, 70 + 30 = 100, ___

5

Create a pattern that starts at 100 and counts back by 5s. Write 5 terms.

Challenge

1

Start at 7. Count by 10s. Which number in your count is between 60 and 70? How do you know without counting?

2

Max counts by 25s to 100 and Lia counts by 5s to 100. Which numbers do they both say?

3

On a hundred chart, start at 12. Move down 3 rows and right 2. Where do you land? Explain.

Check your understanding

Quiz

1.

On a hundred chart, what is directly below 36?

2.

Count by 25s: 25, 50, 75, ___

3.

Which number is not in a count by 10s from 3?

4.

What comes next? 9 + 1 = 10, 19 + 1 = 20, 29 + 1 = 30, ...

5.

When you count by 5s, the ones digits...

6.

What is 10 less than 90?

For parents and teachers

Number patterns help children see how numbers to 100 are related: 10 more, 10 less, 1 more, 1 less, and how skip counting works. This builds place value and mental math.

Common mistakes

  • Mixing up down and across on the hundred chart. Remind your child that down is 10 more because each row has 10 numbers.
  • Losing track crossing a decade (79, 80) or counting by 5s past a hundred-chart row (45, 50, 55). Say the counts aloud together.
  • Thinking 104 is on the chart. The chart stops at 100.

How to help

  • Print or draw a hundred chart and keep it on the fridge.
  • Count coins: nickels by 5s, dimes by 10s, quarters by 25s.
  • Play I'm thinking of a number: It is 10 more than 54. What is it?